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Article

A New Scallop Species, Syncyclonema goyi sp. nov. (Bivalvia, Pectinida, Entoliidae), from the Upper Cenomanian of West Portugal

by
Pedro Miguel Callapez
1,2,3,*,
Fernando Barroso-Barcenilla
1,3,4,
Melani Berrocal-Casero
1,3,4,
José Manuel Brandão
1,5,
Maria José Comas-Rengifo
4,
Rúben Domingos
1,6,
Elsa Gomes
1,2,
Fernando Carlos Lopes
1,2,
Mário Miguel Mendes
1,7,
Senay Ozkaya de Juanas
1,3,
Hélder José Pereira
1,
Jordi Perez-Cano
8,9,10,
Ricardo Jorge Pimentel
1,3,
Vanda Faria dos Santos
3,11,12 and
Manuel Segura
3
1
University of Coimbra, CITEUC—Earth and Space Research Centre, 3040-004 Coimbra, Portugal
2
University of Coimbra, Earth Sciences Department, 3030-790 Coimbra, Portugal
3
PaleoIbérica Research Group, University of Alcalá, 28805 Alcalá de Henares, Spain
4
Grupo de Investigación Procesos Bióticos Mesozoicos, Departamento de Geodinámica, Estratigrafía y Paleontología, Universidad Complutense de Madrid, 28040 Madrid, Spain
5
University of Coimbra, History, Territories, Communities, Pole of NOVA FCSH in the CFE—Centre for Functional Ecology—Science for People & the Planet, 1069-061 Lisbon, Portugal
6
Nova University Lisbon, GeoBioTec, NOVA School of Science and Technology, Campus da Caparica, 2829-516 Caparica, Portugal
7
Fernando Pessoa University, Faculty of Science and Technology, 4249-004 Porto, Portugal
8
Departament de Dinàmica de la Terra i de L’OCEÀ, Facultat de Ciències de la Terra, Universitat de Barcelona-UB, 08028 Barcelona, Spain
9
Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona-UB, 08028 Barcelona, Spain
10
Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona (UB), 08028 Barcelona, Spain
11
University of Lisbon, IDL—Instituto Dom Luiz, 1749-016 Lisbon, Portugal
12
University of Lisbon, Geology Department, 1749-016 Lisbon, Portugal
 
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*
Author to whom correspondence should be addressed.
Geosciences 2026, 16(3), 94; https://doi.org/10.3390/geosciences16030094
Submission received: 30 December 2025 / Revised: 3 February 2026 / Accepted: 18 February 2026 / Published: 24 February 2026
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
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Abstract

A new species of pectinid bivalve, Syncyclonema goyi sp. nov., is described in honour of Professor Antonio Goy, one of the leading stratigraphers who shaped Mesozoic studies in Iberia over the past half century. It represents one of the smaller fossil scallops currently known from the Upper Cretaceous of Europe, alongside a few boreal species previously assigned to the family Entoliidae. The type specimens have orbicular valves, almost smooth, with unequal auricles. The right valve is more convex and bears a well-marked paleal sinus. The sculpture of the shell is weak, exhibiting concentric growth lines and lamellae. However, nearly 90 very small, uniform radial striae are discernible beneath the outer shell layer. This species is frequent in open marine, fine-grained, inner shelf facies of the Tethyan West Portuguese Carbonate Platform, near the main localities of Coimbra, Tentúgal, and Condeixa-a-Nova, in the Baixo Mondego region of West Portugal. It mostly occurs in the upper Cenomanian beds of the Trouxemil Formation, with Euomphaloceras septemseriatum and Vascoceratidae ammonites.

1. Introduction

Scallops are a widespread group of fossil and recent bivalve molluscs of the order Pectinida, recognised by their graceful disc-shaped valves ornated with auricles and radial ribs [1]. They are known through more than 400 extant species [2], and are distributed across a wide range of marine and paralic environments, including deep-water to inner shelf areas, reefs, and lagoons, where a diverse array of adaptations to substrate, salinity, and several other abiotic factors highlights a remarkable level of ecological adaptation.
The fossil record and taxonomic diversity of pectinids (order Pectinida) are even more significant when Cretaceous and Cenozoic strata are concerned [3]. Since their origin and early expansion in the Late Triassic, their diversification has resulted in the documentation of several tens of genera and many hundreds of species.
The European Cretaceous pectinids have been the focus of extensive research since the early 19th century. The systematics of the European boreal and temperate species was reviewed by Dhondt [4,5,6,7,8,9] (and references therein). Further data related to European taxa were also provided by Dhondt [10,11,12,13,14,15,16], Cleevely and Morris [17], Dhondt and Dieni [18,19,20], Malchus et al. [21], Smettan [22], Dhondt and Freneix [23], Morris et al. [24], Schneider et al. [25], Niebuhr et al. [26], and Kunstmüllerová and Košťák [27], among others. These studies highlight several remarkable differences between Boreal assemblages and those of the south European carbonate platforms, where the Pectinida exhibit close affinities with the Tethyan Realm during the Late Cretaceous.
The pectinid bivalves from the Upper Cretaceous of Portugal are mainly known from Cenomanian and lower Turonian mixed and carbonate facies, which are typical of shallow-water, inner shelf carbonate platform palaeoenvironments. Other occasional occurrences have been reported from upper Coniacian and upper Campanian marine units [28,29,30,31].
All these settings and their molluscan fossil assemblages have been documented through a plethora of palaeontological and stratigraphic works such as Sharpe [32,33,34], Choffat [28,35,36,37,38,39,40], Costa [41,42], Moura [43], Soares [44,45,46,47,48,49], Berthou et al. [50,51], Amédro et al. [52], Callapez [53,54,55], Savazzi [56], Barroso-Barcenilla et al. [57,58,59,60], and Ozkaya de Juanas et al. [61].
As a result, there are numerous available data complemented by reference collections housed in the museum of the National Laboratory of Energy and Geology (LNEG; former Geological Survey of Portugal) and the Natural History museums of the universities of Coimbra and Lisbon. These collections yield many species of scallops distributed by the families Neitheidae, Pectinidae, and Entoliidae, with a higher diversity for the genus Neithea, including large specimens adapted to high-energy environments where they are associated with rudists.
The upper Cenomanian carbonate facies mentioned above record the peak of diversity for these assemblages [28,45]. Perhaps due to their minute size and fragility, Entoliidae fossils have been subject to less attention. Consequently, to fill this knowledge gap, our current field research and sampling in the Upper Cretaceous units of the Lusitanian Basin focused on these marine bivalves.
This study is concerned with the taxonomical description of a new species of Syncyclonema, a small scallop found in upper Cenomanian carbonate platform facies of West Portugal (Figure 1a–c). In addition to morphological assessments and comparisons with other Upper Cretaceous Entoliidae representatives, the biostratigraphical range and the palaeoecological setting of the new species are emphasised, considering the Tethyan carbonate platform context where it was discovered.

2. Geographical and Geological Setting

The Cenomanian stage is well-documented in West Portugal as a part of the Albian–Turonian sedimentary record of the West Portuguese Carbonate Platform (WPCP) [31,62,63,64,65,66]. The development of this Tethyan carbonate platform in the West Iberian continental margin occurred during a time of high eustatic sea level, when large areas of Southern Europe were submerged by shallow seas [67,68,69,70,71,72,73].
The carbonate and mixed carbonate–siliciclastic sequences of the WPCP are the largest marine sedimentary units found in the thick Aptian–Maastrichtian post-rift sedimentary cover of the Lusitanian Basin [74,75,76,77,78]. This marginal Atlantic basin was predominantly active during the Late Triassic, Jurassic, and Early Cretaceous rifting episodes, all of which are extensively recorded in the stratigraphic successions of the onshore regions of Portuguese Estremadura and Beira Litoral [30,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94]. In these same areas, and between Lisbon, Coimbra, Figueira da Foz, and Aveiro, the Cenomanian of the WPCP is extensively exposed, always with highly fossiliferous carbonate facies, including a large abundance and diversity of Bivalvia [95,96,97,98].
During the late Cenomanian, the WPCP reached its maximum extent onshore, and large rimmed inner-platform domains with coral and rudist buildups developed between Lisbon, Nazaré, and Leiria [28,31,35,62,63,64]. To the north, these domains were replaced by open shelf areas with cephalopods, whose associations, rich in representatives of Acanthoceratidae and Vascoceratidae, allow for accurate biostratigraphical precision, with emphasis on the Iberian and North African Tethyan basins [99,100,101]. These data are complemented by the occurrence of several taxa of planktic foraminifera (e.g., Heterohelix sp. cf. H. moremani, Guembelitria cretacea, Hedbergella delrioensis, Whiteinella spp., and Helvetoglobotruncana praehelvetica), together with abundant shallow-water benthic taxa, including miliolids, orbitolinids, and alveolinids [102]. Among them, the species Hemicyclammina sigali, Simplalveolina simplex, and Thomasinella punica stand out as typical of many mid-Upper Cenomanian successions from inner to middle shelf carbonate platform environments [31,63,102].
The most complete and thickest upper Cenomanian open shelf non-rudist succession of the WPCP is exposed near the coastal town of Figueira da Foz, where it comprises sequences of limestone and marly limestone beds, currently named as beds “C” to “J” of the Costa d’Arnes Formation (Fm.), and representative of middle shelf palaeoenvironments with ammonites and abundant benthic assemblages of bivalves, gastropods, and echinoids [28,31,37,45,49,54,103,104,105,106,107,108,109,110,111]. With a maximum thickness of 30 m, these beds reveal significant lateral continuity and can be correlated with many other exposures located to the east in the Baixo Mondego region, between the localities of Granja de Ançã, Trouxemil, Barcouço, Coimbra and Condeixa-a-Nova [28,31,45,49,53,110,112,113] (Figure 1d,e).
Near these locations, the upper Cenomanian WPCP lithostratigraphy comprises the Tentúgal Fm. [114] and the Trouxemil Fm. [115], both characterised by successions with facies of marly nodular limestone and massive limestone (beds “C” and “D”), overlaid by beds of laminated marls and sandy marls with limestone nodules, and interbedded nodular marly limestones (beds “E” to “J”) [28,45,49,110,116]. These sequences are transgressive over a thick unit of post-rift coarse alluvial siliciclastics, known as “Lower Coarse Sandstone” [45,49] or the Grada–Barcouço Fm. [115]. The carbonate facies associations record inner shelf, lagoonal, and tidal flat domains where fossil assemblages of bivalves, gastropods, echinoids, and other benthic invertebrate groups, alongside aquatic vertebrates, stand out as remarkable ecostratigraphic and paleoenvironmental indicators for the local shallow and marginal marine domains of the carbonate platform [45,48,49,55,117,118,119].
The occurrence of scallop bivalves, including the new species Syncyclonema goyi, is higher in these upper Cenomanian inner domains of the WPCP, with Vascoceras gamai and other related species of Tethyan ammonites. The stratigraphic succession is representative of the Euomphaloceras septemseriatum and Pseudaspidoceras pseudonodosoides biozones, which partly correlate with the standard biozones of Metoicoceras geslinianum and Neocardioceras juddii [54,120,121,122]. The studied specimens were collected from several localities of these inner domains, with emphasis on Fonte da Areia, the type locality (Figure 2), and Condeixa-a-Nova, where the new species is locally abundant in marly levels with E. septemseriatum and the foraminifera Thomasinella punica and Hemicyclammina sigali and rare Heterohelix sp. and Hedbergella sp. [31,102].

3. Materials and Methods

The studied sample comprises 83 specimens collected from eight exposures with upper Cenomanian beds of the WPCP, and situated between the Trouxemil, Coimbra, and Condeixa-a-Nova localities. All of them are disarticulated valves sampled bed by bed during stratigraphical fieldwork. Their accurate position in the local sections is known, as well as their biostratigraphical setting based on cephalopod assemblage zones.
All specimens were carefully cleaned, numbered with China ink covered by nail varnish, and prepared either manually or mechanically with an electric vibro-tool, at laboratory facilities of the Earth Sciences Department, University of Coimbra. Since the valves of Syncyclonema are thin and fragile, and most specimens are preserved in marly matrix, a dry cleaning was preferred instead of the use of liquids.
A Nikon SMZ800 binocular microscope (Nikon Corporation, Nishioi, Shinagawa-ku, 140-8601 Tokyo, Japan) with a magnification range of 10×–63× was used to observe microstructural details relevant for the taxonomic descriptions. All specimens for morphological description were documented with labels and photographed using a digital camera Olympus© E-M5II (Olympus Corporation, Ishikawa-machi, Hachioji-shi, 192-8507 Tokyo, Japan) at the University of Alcalá (Spain).
As a repository of specimens, the collection has been housed at the Earth Sciences Department, University of Coimbra, Coimbra, Portugal, and is fully available to the scientific community. The new species here described was also recorded under the ZooBank reference: LSID: urn:lsid:zoobank.org:act: 2DF6774F-C712-49C1-8C2F-37BC66B9F182.

4. Systematic Palaeontology (by P. M. Callapez, F. Barroso-Barcenilla, M. Berrocal-Casero, and R. J. Pimentel)

For the systematic above the taxonomic rank of species, the works of Bieler et al. [123,124,125], Huber [126,127], and Carter et al. [128] have been considered, besides the WoRMS [129] database and additional contributions by Newell [130], Moore [131], and Waller [132,133]. The morphological terms follow the terminology adopted by Moore [131] and Dhondt [4]. The following abbreviations have been used: DCTUC—Earth Sciences Department of the University of Coimbra; UA—umbonal angle; LV—left valve; L—length; RV—right valve; UPD—umbo paleal diameter (or height); W—width.
Class: Bivalvia Linnaeus, 1758 [134].
Subclass: Pteriomorphia Beurlen, 1944 [135].
Order Pectinida Gray, 1854 [136].
Superfamily: Entolioidea von Teppner, 1922 [137].
Family: Entoliidae von Teppner, 1922 [138].
Subfamily: Syncyclonematinae Waller, 1978 [132].
Genus: Syncyclonema Meek, 1864 [138].
Type-species: Pecten rigida Hall et Meek, 1856 [139] (= non Sowerby, 1818 [140]; = Pecten halli Gabb, 1861 [141]) by original designation [142].
Species: Syncyclonema goyi sp. nov. (Figure 3 and Figure 4)
Type material: The type specimens designated here, consist of the holotype and 20 paratypes, all of them disarticulated valves.
Holotype: LV (DCTUC-FA8-BR100), from Fonte da Areia, Ançã, West Portugal (upper Cenomanian; units E/G of Trouxemil Fm.) (Figure 3a–d).
Paratypes: RV (DCTUC-FA9-BR54) from Fonte da Areia, Ançã, West Portugal (upper Cenomanian; units E/G of Trouxemil Fm.) (Figure 3e,f); 2 RV (DCTUC-CX16, DCTUC-CX34) from Condeixa-a-Nova, West Portugal (upper Cenomanian; units E/G of Trouxemil Fm.) (Figure 3g–j); 3 LV (DCTUC-CX40, DCTUC-CX14, DCTUC-CX20) and 2 RV (DCTUC-CX22, DCTUC-CX37) from Condeixa-a-Nova, West Portugal (upper Cenomanian; units E/G of Trouxemil Fm.) (Figure 4a,b,i,k,l); RV (5062) from Espigão 2 (upper Cenomanian; unit D of Trouxemil Fm.) (Figure 4c); 4 LV (DCTUC-QB48-BR106, DCTUC-QB48-BR107, DCTUC-QB55-BR113, DCTUC-QB55-BR109) and 2 RV (DCTUC-QB55-BR108, DCTUC-QB55-BR110a-b) from Quinta do Belregão, Trouxemil, West Portugal (upper Cenomanian; units H/J of Trouxemil Fm.) (Figure 4d,e,g,n–p); RV (DCTUC-RF7) from Rios Frios, West Portugal (upper Cenomanian; units E/F of Trouxemil Fm.) (Figure 3f); 2 LV (DCTUC-E34-BR112, DCTUC-E34-BR111) from Espigão, Alcarraques, West Portugal (upper Cenomanian; units H/J of Trouxemil Fm.) (Figure 4h,m); RV (DCTUC-A8-BR53) from Antanhol, West Portugal (basal upper Cenomanian; unit C of Trouxemil Fm.) (Figure 4j).
Additional studied specimens: A total of 65 valves, of which 29 LV and 30 RV are from the stratigraphic sections of Condeixa-a-Nova, West Portugal (upper Cenomanian; units E/G of Trouxemil Fm.), one RV from Lapa, Cantanhede, West Portugal (upper Cenomanian; units E/I of Trouxemil Fm.), three RV from Espigão, Alcarraques, West Portugal (upper Cenomanian; units H/J of Trouxemil Fm.), and two RV from Quinta do Belregão, Trouxemil, West Portugal (upper Cenomanian; units H/J of Trouxemil Fm.).

4.1. Generic Diagnosis

The emended diagnosis proposed by Speden [142] and expanded by Dhondt [4] to include medium-sized species, is adopted here:
“Small [to medium sized], subequivalve, subequilateral. Shell of vitreous appearance, thin, of three layers: thin outer homogeneous or prismatic layer, middle layer of zigzag lamellar structure, and thin inner complex cross-lamellar layer. Ornament sub-macroscopic, except on ears, of fine non-punctate diverging radial striae, fine growth striae, and coarser irregular growth lamellae tending to give reticulate pattern. Radial striae strongest at ventral margin and on dorsal flanks of disc of shell, sometimes absent on centre of disc. Concentric lamellae strong on ears. Interior of shell sometimes with low faint rounded concentric ridges and fine radial striae. Concentric undulations sometimes evident on external surface, particularly on the right valve. Anterior auricle equal to or significantly larger than the posterior.
Anterior auricle of the right valve distinctly separated from disc of shell, fasciole very narrow, and byssal sinus deep, open V-shaped. No ctenolium. Dorsal margin of right valve overlaps that of the left valve. Each auricle with one thin cardinal crus below the ligament band, that on the posterior auricle of each valve extending usually only about two-thirds of the distance towards the posterior margin. One relatively long strong tooth-like process on either side of the resilifer pit of the right valve. No auricular crura. Adductor muscle impression small, subcircular, sited above two thirds the height of shell adjacent to basal part of posterior auricle. Pallial line continuous” [142].

4.2. Derivatio Nominis

The new species is named in honour of Antonio Goy, Emeritus Professor of the Complutense University of Madrid, one of the leading stratigraphers who shaped Mesozoic studies in Iberia over the past half century.

4.3. Type Locality

Fonte da Areia, Ançã, West Portugal (40°15′22″ N; 8°29′59″ W) (Figure 1d,e).

4.4. Type Horizon

Middle upper Cenomanian (Trouxemil Fm., West Coimbra, West Portugal).

4.5. Diagnosis

Small Syncyclonema species with a thin, fragile shell, with orbicular shape. Slightly convex valves, rounded, with moderately asymmetrical discs and rather small, unequal auricles. Hinge straight, normal to the dorso-ventral axis, with a length of about two-thirds of the disc. Auricles unequal. RV bears a long anterior auricle with rounded outline, separated from the disc by a deep byssal notch; the posterior auricle is subtriangular shaped, obtuse-angled, and curved at the extremity of the dorsal hinge-line, with a height close to 30% of UPD. LV anterior auricle almost twice the size of the posterior, slightly acute-angled and rounded at the dorsal end corner; the opposite auricle is similar to the posterior auricle of RV. Sculpture very week, with numerous concentric growth lines over the disc and auricles, regularly and closely spaced, being more marked and lamellose along the ventral sides of the valves. Anterior auricles with lamellae in some specimens. Radial ornament sub-macroscopic, consisting of about 90 fine striae, closely spaced, diverging towards the lateral and ventral edges of the valves (Table 1).

4.6. Geographical and Stratigraphic Distribution

The genus Syncyclonema Meek, 1864 is restricted to the Cretaceous Period and found in the United States of America and Europe. In the European basins, it is known from the Aptian to Maastrichtian [4].
The new species occurs in the Baixo Mondego region near Coimbra, in West Central Portugal. It was reported from the localities of Trouxemil, Adões and Sargento-Mor, near Coimbra, and Fonte da Areia (Ançã), Antanhol and Condeixa-a-Nova, in upper Cenomanian beds of the WPCP with carbonate and mixed facies, interpreted as the inner shelf domains of the carbonate platform (Trouxemil Fm.). It is especially abundant in the locality of Condeixa-a-Nova, where a fossil-rich succession of marly strata correlative of the Euomphaloceras septemseriatum ammonite biozone occurs. The whole stratigraphical distribution presently known ranges from the basal upper Cenomanian (Calycoceras guerangeri biozone), where the species is uncommon, to the uppermost part of this stage (Pseudaspidoceras pseudonodosoides biozone).

4.7. Discussion

The type specimens and the supplementary studied materials show all the morphological characteristics attributed to the genus Syncyclonema Meek, 1864, as redescribed by Speden [142] and adopted by Dhondt [4] and subsequent work. In addition to the size and shape of their discs and asymmetrical auricles, they are characterised by an RV with a well-developed byssal notch in the anterior auricle, which is absent in the opposite valve. Besides a fine sculpture with spaced concentric growth lines and lamellae, there is also a micro-ornamentation present on the middle shell layer, consisting of profuse and divergent radial striae. They are only visible under magnification in valves with the three layers of the shell preserved, with particular emphasis on the holotype, giving some of the vermiculate Camptonectes-like appearance mentioned by Dhondt [4].
Although not uncommon in the studied area, being only locally abundant in the exposures of Condeixa-a-Nova, and mostly in the upper beds of the Trouxemil Fm., this small scallop species remained unknown in the research developed in the Cenomanian carbonate formations previous to 1992 [53]. The possible reason is the consequence of its small size and the poor preservation conditions of most specimens. The first valves found were tentatively classified as Syncyclonema ?simplicia by Callapez and Soares [143] in the absence of more diagnostic material.
Dhondt [4] reviewed in detail the various representatives of the genus in the Temperate-Boreal realm, including three small Syncyclonema species comparable to the new Portuguese one: S. greppini (Aptian–Albian), S. gamsensis (Santonian–Maastrichtian), and S. haggi (Turonian–Maastrichtian). However, they have different ages and biogeographic ranges compared to the Portuguese specimens. Their size is also comparatively larger and they differ in the number and shape of their radial striae, as well as in the RV and LV auricles.
Syncyclonema goyi sp. nov. also resembles some Upper Cretaceous species from central and southern areas of the Western Interior of the United States, in North America, such as S. halli (Campanian–Maastrichtian), S. inconspicua (Albian), and especially S. simplicia (Santonian–Maastrichtian). However, differences in auricle size and shape, as well as the number of striae, also persist, which enable the distinction of S. goyi sp. nov. from the previously mentioned species.

5. Range and Palaeoenvironment

The occurrence of Cretaceous Syncyclonema has been described from a wide variety of marine facies ranging from inner to outer shelf environments, with many species adapted to shallow water, carbonated, or mixed carbonate–siliciclastic, soft substrates, besides others known from deeper, more distal basin settings [144,145,146,147]. Most taxa have been found in North America, e.g., [142,148,149,150,151], Northwest and Central Europe, and former USSR, e.g., [4,14,21,152,153], suggesting short- to long-range dispersals within the Temperate-Boreal realm. These biogeographical patterns can be interpreted as adaptations to colder aquatic palaeoenvironments, ecologically diverse from the contemporary lower-latitude neritic assemblages of the Tethyan Realm containing Pectinida representatives.
Compared to these contexts, the occurrence of Syncyclonema goyi sp. nov. in upper Cenomanian beds of the WPCP stands out, as it confirms the data of Dhondt [12] for Spain, that this group of Entoliidae also existed in the Tethyan areas of Southern Europe with non-rudist, carbonate platform environments, where the sub-tropical conditions of this vast biogeographic realm prevailed during the high sea-level intervals of the Late Cretaceous [67,68,69,154].
The studied area where the new species occurs corresponds to the proximal domains of the WPCP in the Baixo Mondego region of West Portugal, between Figueira da Foz and Coimbra [30,54,55,110,155]. These are characterised by several upper Cenomanian fossil-rich inner shelf, lagoonal, and tidal flat domains with carbonate and mixed carbonate–siliciclastic facies yielding shallow-water invertebrate assemblages, where Tethyan molluscs such as Neithea dutrugei, N. hispanica, Costagyra olisiponensis, Ceratostreon flabellatum, Tylostoma ovatum, T. torrubiae, and Ampullina puctata are among the most widespread faunal elements [45,49,53].
The occurrence of Syncyclonema goyi sp. nov. in this setting, as well as the lithofacies and the invertebrate assemblages associated with the sampled specimens, seems to indicate that this small scallop species preferred shallow-water, infralittoral environments with soft and oxygenated substrates located within the photic zone. However, it was absent from intertidal and lagoonal settings. Like many recent Pectinida with smooth and thin valves, and unequal auricles with a well-developed byssal notch, this minute Cretaceous scallop was a typical suspension-feeder that lived attached by a bissus to hard parts of the substrate, including living as an epizoan to other shells or macroalgae available in the local environment [156,157,158,159,160].
The species should also have been rather tolerant of substrate composition, as we found specimens in a variety of lithofacies, ranging from limestone and marly limestone to sandy limestone, micaceous sandstone, and marl. Among these, the carbonate lithofacies generally correspond to wackstone–packstone biomicrites rich in invertebrate microremains, benthic foraminifera, and dasicladacean algae [31,45,49,62,161].
However, Syncyclonema goyi sp. nov appears to be more abundant in the following depositional settings:
(a)
Shallow infralittoral facies of micaceous, yellowish sandy limestones interbedded with fine-grained micaceous sandstones. These beds are characterised by the abondance of small tubes of serpulid worms, together with Rhynchostreon, small infaunal bivalves (e.g., Nuculana), gastropods (e.g., Aporrhais), and undetermined Decapoda claws. These invertebrates are part of a low-diversity faunal assemblage dominated by epifaunal suspension feeders (Figure 5), described as the “Syncyclonema ?simplicia and Serpula” fossil-association [53,54]. They characterise a shallow, low- to moderate-energy environment with elevated nutrient levels. According to Bishop [162], Syncyclonema-dominated assemblages may co-occur with Decapoda crustaceans (predominantly detritus feeders), where bioturbation by decapods potentially enhances nutrient recycling for suspension-feeding bivalves. This interpretation is consistent with the presence of undisturbed micaceous laminae, indicating limited sediment reworking.
(b)
Shallow infralittoral facies of finely laminated greyish marls. These beds are restricted to a limited area near Condeixa-a-Nova, adjacent to the southern margin of the studied region. The new species Syncyclonema goyi sp. nov. is highly abundant here, with its disarticulated valves co-occurring alongside crushed shells and moulds of Nuculana sp., small Pseudoptera anomala, Neithea hispanica, and Paraesa cf. faba, sometimes accompanied by numerous fragments of macroalgal calcified thalli. This assemblage can be interpreted as a relict of a suspension-feeder-dominated palaeocommunity adapted to a low-energy, fully marine environment with argillaceous, fine-grained substrates. The relatively oxygenated conditions, likely maintained by periodic currents or bioturbation, combined with the proliferation of macroalgae (possibly forming hardgrounds), provided attachment substrates for small byssate bivalves.
From studies of modern aquatic environments, it is well documented that many bivalve species have biotic interactions with algae. At least 30 species, including the large Indo-Pacific Tridacna, are symbiotic with endozoic microalgae [163,164]. Many others, including several mussels and scallops, spend at least part of their life cycles in subtidal environments within the photic zone associated with macroalgal beds, where interactions of mutualism, commensalism, epibiosis, or parasitism can occur, e.g., [165,166,167,168]. Some of these interactions likely have existed since the early diversification and evolution of the Pectinida, and analogies can be drawn with Cretaceous species such as Syncyclonema goyi sp. nov. In this example, shell shape and auricle morphology clearly indicate an epibiotic lifestyle, as observed in many modern byssate scallops, which attach to a diversity of hard substrates, including the stems or thalli of macroalgae [169,170]. Such epibiosis strategy is even more frequent during post-larval juvenile stages, when algal beds can act as refugia [171,172,173,174]. In the present case, small Syncyclonema individuals would have locally benefit from the calcified macroalgae available in their palaeoenvironment, which provided an advantageous substrate for byssate fixation.

6. Conclusions

The occurrence Syncyclonema goyi sp. nov. in the upper Cenomanian beds of the WPCP (Baixo Mondego region of West Portugal) highlights the relevance of pteriomorphs in shallow marine assemblages of the European Cretaceous. Notably, other species mentioned by Dhondt [4] within this group exhibit temperate–boreal biogeographic distributions throughout the Aptian–Maastrichtian interval.
The new species described here is one of the smallest Upper Cretaceous European Pectinida. Its discovery extends the range of this amphiatlantic genus from the Western Interior Seaway of North America and the Northwest and Central Europe to the non-rudist, carbonate platform facies of the Tethyan Realm. This finding provides a foundation for further research, particularly concerning the occurrence and diversification of these Entoliidae in Iberian and North African contexts.
Syncyclonema goyi sp. nov is characterised by orbicular valves, almost smooth, with unequal auricles, where the right valve is slightly more convex and bears a well-marked byssal notch. The shell sculpture consists of thin concentric growth lines and lamellae, with about 90 radial striae discernible below the outer shell layer.
Disarticulated valves and moulds of this species are quite common in open-marine, fine-grained inner shelf facies of the Tethyan West Portuguese Carbonate Platform (WPCP). In addition to the type locality of Fonte da Areia (Ançã), they have been found in several exposures near Coimbra, Trouxemil, and Condeixa-a-Nova localities, mostly in upper Cenomanian layers with Euomphaloceras septemseriatum and Vascoceratidae ammonites.

Author Contributions

Conceptualisation, P.M.C., F.B.-B., M.B.-C. and R.J.P.; methodology, P.M.C., F.B.-B., M.B.-C. and R.J.P.; formal analysis, P.M.C., F.B.-B., M.B.-C. and R.J.P.; investigation, P.M.C., F.B.-B., M.B.-C., J.M.B., M.J.C.-R., R.D., E.G., F.C.L., M.M.M., S.O.d.J., H.J.P., J.P.-C., R.J.P., V.F.d.S. and M.S.; writing—original draft preparation, P.M.C., F.B.-B., M.B.-C., J.M.B., M.J.C.-R., R.D., E.G., F.C.L., M.M.M., S.O.d.J., H.J.P., J.P.-C., R.J.P., V.F.d.S. and M.S.; writing—review and editing, P.M.C. and R.J.P.; visualisation, P.M.C., F.B.-B. and M.B.-C.; supervision, P.M.C. and F.B.-B.; funding acquisition, P.M.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was co-funded by FCT under the contract of the UID/Multi/00611/2020 (DOI https://doi.org/10.54499/UIDB/00611/2020) research project through CITEUC, FEDER (European Regional Development Fund) through COMPETE 2020—Operational Program Competitiveness and Internationalization (project: POCI-01-0145-FEDER-006922), and the projects LA/P/0069/2020 granted to the Associate Laboratory ARNET and GeoBioTec UID/04035/2025 (DOI https://doi.org/10.54499/UID/04035/2025).

Data Availability Statement

The original contributions presented in this study are included in the article; any further inquiries can be directed to the corresponding author. Taxonomical data are based in a collection of type specimens housed at the Earth Sciences Department, University of Coimbra, Coimbra, Portugal, and available for the scientific community.

Acknowledgments

The authors thank the four anonymous reviewers for their helpful constructive comments and corrections on the manuscript. We are grateful to CITEUC—Earth and Space Research Centre of the University of Coimbra (Portugal), and to the PaleoIbérica Research Group of the University of Alcalá (Spain), for all the institutional support available for this scientific study.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of the data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Cox, I. The Scallop. Studies of a Shell and Its Influences on Humankind; “Shell” Transport and Trading Company: London, UK, 1957; pp. 1–135. [Google Scholar]
  2. Rombouts, A. Guidebook to Pecten Shells. Recent Pectinidae and Propeamussidae of the World; Robert Hale: London, UK, 1991; pp. 1–157. [Google Scholar]
  3. Kauffman, E.G. Cretaceous Bivalvia. In Atlas of Paleobiogeography; Hallam, A., Ed.; Elsevier: Amsterdam, The Netherlands, 1973; pp. 353–383. [Google Scholar]
  4. Dhondt, A.V. Systematic revision of Entolium, Propeamussium (Amusiidae) and Syncyclonema (Pectinidae, Bivalvia, Mollusca) of the European boreal Cretaceous. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1971, 47, 1–95. [Google Scholar]
  5. Dhondt, A.V. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 1: Camptonectes. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1972, 48, 1–60. [Google Scholar]
  6. Dhondt, A.V. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 2: Lyropecten. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1972, 48, 1–81. [Google Scholar]
  7. Dhondt, A.V. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 3: Chlamys and Mimachlamys. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1973, 49, 1–134. [Google Scholar]
  8. Dhondt, A.V. Systematic revision of the subfamily Neitheinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Mém. Inst. R. Sci. Nat. Belg. 1973, 176, 1–99. [Google Scholar]
  9. Dhondt, A.V. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 4: Merklinia. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1976, 52, 1–38. [Google Scholar]
  10. Dhondt, A.V. Répartition des bivalves (sans inocérames ou rudistes) dans le Crétacé moyen. Cretac. Res. 1981, 2, 307–318. [Google Scholar] [CrossRef]
  11. Dhondt, A.V. Bivalvia (Mollusca) from the Maastrichtian of Hemmoor (NW Germany) and their palaeobiogeographical affinities. Geol. Jahrb. 1982, A61, 73–107. [Google Scholar]
  12. Dhondt, A.V. Some Spanish Cretaceous bivalves. Cuad. Geol. Ibér. 1983, 8, 847–865. [Google Scholar]
  13. Dhondt, A.V. Bivalves ptériomorphes du Sénonien dans le Bassin parisien et le sud-ouest de la France. Géol. Méditerr. 1985, 10, 213–218. [Google Scholar] [CrossRef]
  14. Dhondt, A.V. Bivalves from the Hochmoos Formation (Gosau-Group, Oberösterreich, Austria). Ann. Nat. Hist. Mus. Vienna 1987, 88A, 41–101. [Google Scholar]
  15. Dhondt, A.V. Palaeogeographic distribution of Cretaceous Tethyan non-rudist bivalves. In New Aspects on Tethyan Cretaceous Fossil Assemblages; Kollmann, H.A., Zapfe, H., Eds.; Springer: Berlin/Heidelberg, Germany, 1992; Volume 9, pp. 75–94. [Google Scholar]
  16. Dhondt, A.V. Upper Cretaceous bivalves from Tercis, Landes, SW France. Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1993, 63, 211–259. [Google Scholar]
  17. Cleevely, R.J.; Morris, N.J. An introduction to molluscs and bivalves. In Fossils of the Chalk. Palaeontological Association Field Guides to Fossils, 2; Smith, A.B., Batten, D.J., Eds.; The Palaeontological Association: London, UK, 1987; pp. 99–160. [Google Scholar]
  18. Dhondt, A.V.; Dieni, I. Rudist-associated Cretaceous bivalves. Saito Ho-On Kai Spec. Publ. 1991, 3, 193–200. [Google Scholar]
  19. Dhondt, A.V.; Dieni, I. Non rudistid bivalves from Cretaceous rudist formations. Geol. Romana 1992, 28, 211–218. [Google Scholar]
  20. Dhondt, A.V.; Dieni, I. Non-rudistid bivalves from Late Cretaceous rudist limestones of NE Italy (Col dei Schiosi and Lago di S. Croce areas). Mem. Sci. Geol. 1993, 45, 165–241. [Google Scholar]
  21. Malchus, N.; Dhondt, A.V.; Tröger, K.A. Upper Cretaceous bivalves from the Glauconie de Lonzée near Gembloux (SE Belgium). Bull. Inst. R. Sci. Nat. Belg. Sci. Terre 1994, 64, 109–149. [Google Scholar]
  22. Smettan, K. Bivalven, Gastropoden und Serpuliden aus den Branderfleckschichten (Cenoman) der Fahrenbergmulde (Nördliche Kalkalpen, Bayern): Taxonomie und palökologie. Zitteliana 1997, 21, 99–158. [Google Scholar]
  23. Dhondt, A.V.; Freneix, S. Cretaceous bivalves and Alcide d’Orbigny. Comptes Rendus Palevol 2002, 1, 555–564. [Google Scholar] [CrossRef]
  24. Morris, N.J.; Knight, R.I.; Cleevely, R.J. Bivalves. In Fossils of the Gault Clay; Young, J.R., Gale, A.S., Knight, R.I., Smith, A.B., Eds.; Palaeontological Association Field Guides to Fossils, 12; The Palaeontological Association: London, UK, 2010; pp. 59–85. [Google Scholar]
  25. Schneider, S.; Jager, M.; Kroh, A.; Mitterer, A.; Niebuhr, B.; Vodražka, R.; Wilmsen, M.; Wood, C.J.; Zagoršek, K. Silicified Sea life. Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to lower Turonian Wellheim Formation, Bavaria, southern Germany). Acta Geol. Pol. 2013, 63, 555–610. [Google Scholar] [CrossRef]
  26. Niebuhr, B.; Schneider, S.; Wilmsen, M. Kreide-Fossilien in Sachsen, Teil 1. Cretaceous fossils of Saxony, part 1.–5. Muscheln. 5. Bivalves. Geol. Saxonica J. Cent. Eur. Geol. 2014, 60, 83–168. [Google Scholar]
  27. Kunstmüllerová, L.; Košťák, M. Changes in bivalve assemblages at the onset of the OAE2 event in the Peri-Tethyan area (Bohemian Cretaceous Basin). Cretac. Res. 2024, 153, 105704. [Google Scholar] [CrossRef]
  28. Choffat, P.L. Recueil de Monographies Stratigraphiques sur le Système Crétacique du Portugal, Deuxième Etude, Le Crétacé Supérieur au Nord du Tage; Direction des Services Géologiques du Portugal: Lisbonne, Portugal, 1900; pp. 1–287. [Google Scholar]
  29. Beauvais, M.; Berthou, P.Y.; Lauverjat, J. Le gisement campanien de Mira (Beira Litorale, Portugal): Sédimentologie, micropaléontologie, révision des Madréporaires. Comun. Serv. Geol. Port. 1975, 59, 37–58. [Google Scholar]
  30. Ribeiro, A.; Antunes, M.T.; Ferreira, P.; Rocha, R.B.; Soares, A.F.; Zbyszewsky, G.; Almeida, F.M.; Carvalho, D.; Monteiro, J. Introduction à la Géologie Générale du Portugal; Serviços Geológicos de Portugal: Lisboa, Portugal, 1979; pp. 1–114. [Google Scholar]
  31. Lauverjat, J. Le Crétacé Supérieur dans le Nord du Bassin Occidental Portugais. Ph.D. Thesis, Université Pierre et Marie Curie, Paris, France, 1982. [Google Scholar]
  32. Sharpe, D. On Tylostoma, a proposed genus of gasteropodous molluscs. Q. J. Geol. Soc. Lond. 1849, 5, 375–380. [Google Scholar] [CrossRef]
  33. Sharpe, D. Remarks on the genus Nerinea, with an account of the species found in Portugal. Q. J. Geol. Soc. Lond. 1850, 6, 101–115. [Google Scholar] [CrossRef]
  34. Sharpe, D. On the Secondary District of Portugal which lies on the North of the Tagus. Q. J. Geol. Soc. Lond. 1850, 6, 135–201. [Google Scholar] [CrossRef]
  35. Choffat, P.L. Recueil de Monographies Stratigraphiques sur le Système Crétacique du Portugal, Première Etude, Contrée de Cintra, de Bellas et de Lisbonne; Section des Travaux Géologiques du Portugal: Lisbonne, Portugal, 1885; pp. 1–68. [Google Scholar]
  36. Choffat, P.L. Recueil d’études Paléontologiques sur la Faune Crétacique du Portugal, I—Espèces Nouvelles ou peu Connues; Section des Travaux Géologiques du Portugal: Lisbonne, Portugal, 1886; pp. 1–40. [Google Scholar]
  37. Choffat, P.L. Note sur le Crétacique des environs de Torres Vedras, de Peniche et de Cercal. Comun. Commissão Serv. Geol. Port. 1891, 2, 171–215. [Google Scholar]
  38. Choffat, P.L. Recueil d’Etudes Paléontologiques sur la Faune Crétacique du Portugal, II—Les Ammonées du Bellasien, des Couches à Neolobites vibrayeanus, du Turonien et du Sénonien; Section des Travaux Géologiques du Portugal: Lisbonne, Portugal, 1898; pp. 1–45. [Google Scholar]
  39. Choffat, P.L. Recueil d’Etudes Paléontologiques sur la Faune Crétacique du Portugal, Vols. III–IV—Mollusques du Sénonien à Faciès Fluviomarin—Espèces Nouvelles ou Peu Connues; Direction des Services Géologiques du Portugal: Lisbonne, Portugal, 1901; pp. 1–84. [Google Scholar]
  40. Choffat, P.L. Espèces nouvelles ou peu connues du Mésozoïque portugais. II—Espèces du Crétacique. J. Conchol. 1906, 54, 33–41. [Google Scholar]
  41. Costa, J.C. O Neocretácico da Beira Litoral. Publ. Mus. Lab. Miner. Geol. Fac. Ciênc. Porto 1937, 5, 1–33. [Google Scholar]
  42. Costa, J.C. Os fósseis de Aveiro e algumas considerações geológicas. Arq. Aveiro 1941, 7, 83–98. [Google Scholar]
  43. Moura, A. Alguns equinídeos regulares fósseis da Costa d’Arnes, Alfarelos, Coimbra. Mem. Notíc. 1958, 45, 61–72. [Google Scholar]
  44. Soares, A.F. Considerações sobre as Exogyra columba Lam., Exogyra flabellata Gold. e Exogyra olisiponensis Sharpe do Cretácico das regiões de Coimbra e Figueira da Foz. Mem. Notíc. 1960, 49, 21–40. [Google Scholar]
  45. Soares, A.F. Estudo das formações pós-jurássicas das regiões de entre Sargento-Mor e Montemor-o-Velho (margem direita do Rio Mondego). Mem. Notíc. 1966, 62, 1–343. [Google Scholar]
  46. Soares, A.F. Nouveau genre de Lamellibranche Hétérodonte du Crétacé du Portugal. Mem. Notíc. 1967, 64, 58–67. [Google Scholar]
  47. Soares, A.F. Uma nova espécie da família Trochidae—Calliostoma (Calliostoma) choffati—No Cretácico Superior de Portugal Metropolitano. Rev. Ciênc. Geol. Ser. A 1968, 1, 49–53. [Google Scholar]
  48. Soares, A.F. Estudo da distribuição dos ostreídeos do Cretácico Superior (Cenomaniano superior e Turoniano inferior) na região entre Sargento-Mor e Montemor-o-Velho (Margem direita do Rio Mondego). Rev. Ciênc. Geol. Ser. A 1968, 1, 55–72. [Google Scholar]
  49. Soares, A.F. Contribuição para o estudo do Cretácico em Portugal (o Cretácico Superior da Costa de Arnes). Mem. Notíc. 1972, 74, 1–56. [Google Scholar]
  50. Berthou, P.Y.; Brower, J.C.; Reyment, R.A. Morphometrical study of Choffat’s vascoceratids from Portugal. Bull. Geol. Inst. Univ. Upps. 1975, 6, 73–83. [Google Scholar]
  51. Berthou, P.Y.; Chancellor, G.; Lauverjat, J. Revision of the Cenomanian–Turonian Ammonite Vascoceras Choffat, 1898, from Portugal. Comun. Serv. Geol. Port. 1985, 71, 55–79. [Google Scholar]
  52. Amédro, F.; Berthou, P.Y.; Lauverjat, J. Nouvelles preuves de l’apparition au Cénomanien supérieur des premiers Vascoceras dans la série type de la basse vallée du Rio Mondego (Beira Litoral, Portugal). Bol. Soc. Geol. Port. 1980, 22, 153–162. [Google Scholar]
  53. Callapez, P.M. Estudo Paleoecológico dos Calcários de Trouxemil (Cenomaniano–Turoniano) na Região Entre a Mealhada e Condeixa-a-Nova (Portugal Central). MSc Thesis, University of Coimbra, Coimbra, Portugal, 1992. [Google Scholar]
  54. Callapez, P.M. Estratigrafia e Paleobiologia do Cenomaniano–Turoniano. O Significado do eixo da Nazaré-Leiria-Pombal. Ph.D. Thesis, University of Coimbra, Coimbra, Portugal, 1998. [Google Scholar]
  55. Callapez, P.M. Palaeobiogeographic evolution and marine faunas of the Mid-Cretaceous Western Portuguese Carbonate Platform. Thalassas 2008, 24, 29–52. [Google Scholar]
  56. Savazzi, E. Functional morphology and autecology of Pseudoptera (bakevelliid bivalves, Upper Cretaceous of Portugal). Palaeogeogr. Palaeoclimatol. Palaeoecol. 1984, 46, 313–324. [Google Scholar] [CrossRef]
  57. Barroso-Barcenilla, F.; Callapez, P.M.; Soares, A.F.; Segura, M. Cephalopod assemblages and depositional sequences from the upper Cenomanian and lower Turonian of the Iberian Peninsula (Spain and Portugal). J. Iber. Geol. 2011, 37, 9–28. [Google Scholar] [CrossRef]
  58. Barroso-Barcenilla, F.; Callapez, P.M.; Segura, M. Revision and new data of the Coniacian ammonite genus Hemitissotia in the Iberian Peninsula (Spain and Portugal). Paläontol. Z. 2013, 87, 201–217. [Google Scholar] [CrossRef]
  59. Barroso-Barcenilla, F.; Brandão, J.M.; Callapez, P.M.; Santos, V.F. Rediscovery of the holotypes of the Cenomanian (Upper Cretaceous) ammonites Vascoceras gamai Choffat, 1898, and Vascoceras barcoicense (Choffat, 1898). Cretac. Res. 2015, 56, 647–650. [Google Scholar] [CrossRef]
  60. Barroso-Barcenilla, F.; Antunes, M.T.; Brandão, J.M.; Callapez, P.M.; Santos, V.F. The d’Orbigny Palaeontological Collection of the National Museum of Natural History and Science, Lisbon, Portugal: Historical perspective and revision of Cretaceous Cephalopoda. Geodiversitas 2018, 40, 505–519. [Google Scholar] [CrossRef]
  61. Ozkaya de Juanas, S.; Barroso-Barcenilla, F.; Berrocal-Casero, M.; Callapez, P. Virtual fossils for widening Geoeducation approaches: A case study based on the Cretaceous sites of Figueira da Foz (Portugal) and Tamajón (Spain). Geosciences 2023, 13, 16. [Google Scholar] [CrossRef]
  62. Berthou, P.Y. Le Cénomanien de l’Estrémadure portugaise. Mem. Serv. Geol. Port. 1973, 23, 1–169. [Google Scholar]
  63. Berthou, P.Y. La transgression cénomanienne dans le Bassin Occidental Portugais. Geol. Mediterr. 1978, 5, 31–38. [Google Scholar] [CrossRef]
  64. Berthou, P.Y. Résumé synthétique de la stratigraphie et de la paléogéographie du Crétacé moyen et supérieur du bassin occidental portugais. Geonovas 1984, 7, 99–120. [Google Scholar]
  65. Berthou, P.Y.; Lauverjat, J. Essai de synthèse paléogéographique du Bassin Occidental Portugais au cours du Crétacé Supérieur. Ciênc. Terra 1979, 5, 121–144. [Google Scholar]
  66. Berthou, P.Y.; Ferreira Soares, A.; Lauverjat, J. Portugal, in: Mid Cretaceous Events Iberian Field Conference 77, Guide-book 1. Cuad. Geol. Ibér. 1979, 5, 31–124. [Google Scholar]
  67. Hancock, J.M.; Kauffman, E.G. The great transgressions of the Late Cretaceous. J. Geol. Soc. Lond. 1979, 136, 175–186. [Google Scholar] [CrossRef]
  68. Haq, B.U.; Hardenbol, J.; Vail, P.R. Mesozoic and Cenozoic Chronostratigraphy and Eustatic Cycles. In Sea-Level Changes, an Integrated Approach; Wilgus, C.K., Hastings, B.S., Kendall, C.G.S.C., Posamentier, H., Ross, C.A., Wagoner, J.C., Eds.; SEPM Special Publication: Tulsa, OK, USA, 1988; Volume 42, pp. 71–108. [Google Scholar]
  69. Hart, M.B. Cretaceous sea level changes and global eustatic curves; evidence from SW England. Proc. Ussher Soc. 1990, 7, 268–272. [Google Scholar]
  70. Hancock, J.; Kennedy, W.J.; Cobban, W. A correlation of the upper Albian to basal Coniacian sequences of Northwest Europe, Texas and the United States Western Interior. In The Evolution of the Western Interior Basin; Caldwell, W., Kauffman, E.G., Eds.; Special Paper; GAC: St. John’s, NL, USA, 1993; Volume 39, pp. 453–476. [Google Scholar]
  71. Hardenbol, J.; Thierry, J.; Farley, M.B.; Jacquin, T.; de Graciansky, P.C.; Vail, P.R. Mesozoic and Cenozoic sequence chronostratigraphic framework of European basins, Chart 1, Mesozoic and Cenozoic sequence chronostratigraphic chart. In Mesozoic and Cenozoic Sequence Stratigraphy of European Basins; Graciansky, P.C., Hardenbol, J., Jacquin, T., Vail, P., Eds.; SEPM Special Publication: Tulsa, OK, USA, 1998; Volume 60, pp. 3–13. [Google Scholar]
  72. Haq, B.U. Cretaceous eustasy revisited. Glob. Planet. Change 2014, 113, 44–58. [Google Scholar] [CrossRef]
  73. Callapez, P.M.; Gil Gil, J.; Garcia-hidalgo, J.; Segura, M.; Barroso-Barcenilla, F.; Carenas, B. The Tethyan oyster Pycnodonte (Costeina) costei (Coquand, 1869) in the Coniacian (Upper Cretaceous) of the Iberian Basin (Spain): Taxonomic, palaeoecological and palaeobiogeographical implications. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2015, 435, 105–117. [Google Scholar] [CrossRef]
  74. Dinis, J.L.; Trincão, P. Controlos deposicionais e biostratigrafia da base dos ‘grés belasianos’ (Aptiano, Bacia Lusitaniana). Comum. Serv. Geol. Port. 1991, 77, 89–102. [Google Scholar]
  75. Dinis, J.L. Estratigrafia e Sedimentologia da Formação da Figueira da Foz—Aptiano a Cenomaniano do Sector Norte da Bacia Lusitânica. Ph.D. Thesis, University of Coimbra, Coimbra, Portugal, 1999. [Google Scholar]
  76. Dinis, J.L. Definição da Formação da Figueira da Foz—Aptiano a Cenomaniano do sector central da margem oeste ibérica. Comun. Inst. Geol. Min. 2001, 88, 127–160. [Google Scholar]
  77. Dinis, J.L.; Rey, J.; Graciansky, P.C. Le Bassin Lusitanien (Portugal) à l’Aptien supérieur–Albien, organisation séquentielle, proposition de corrélations, évolution. Comptes Rendus Geosci. 2002, 334, 757–764. [Google Scholar] [CrossRef]
  78. Dinis, J.L.; Rey, J.; Cunha, P.P.; Callapez, P.M.; Reis, R.P. Stratigraphy and allogenic controls on the western Portugal Cretaceous, an updated synthesis. Cretac. Res. 2008, 29, 772–780. [Google Scholar] [CrossRef]
  79. Wilson, R.C.L. A reconnaissance study of Upper Jurassic sediments of the Lusitanian Basin. Ciênc. Terra 1979, 5, 53–84. [Google Scholar]
  80. Wilson, R.C.L. Mesozoic development of the Lusitanian Basin, Portugal. Rev. Soc. Geol. Esp. 1988, 1, 393–407. [Google Scholar]
  81. Rey, J. Le Crétacé Inférieur de la marge atlantique portugaise: Biostratigraphie, organisation séquentielle, évolution paléogéographique. Ciênc. Terra 1979, 5, 97–121. [Google Scholar]
  82. Rey, J. Dynamique et paléoenvironnements du bassin mésozoïque d’Estremadura (Portugal), au Crétacé Inférieur. Cretac. Res. 1982, 3, 103–111. [Google Scholar] [CrossRef]
  83. Rey, J. Stratigraphie séquentielle et séquences de dépôt dans le Crétacé Inférieur du Bassin Lusitanien. Ciênc. Terra 2006, 6, 1–120. [Google Scholar]
  84. Rey, J. La dynamique sédimentaire des Bassins Lusitanien et de l’Algarve au Crétacé Inférieur. Ciênc. Terra 2010, 17, 45–52. [Google Scholar]
  85. Wilson, R.C.L.; Hiscott, R.; Willis, M.; Gradstein, F. The Lusitanian Basin of west central Portugal, Mesozoic and Tertiary tectonic, stratigraphic and subsidence history. In Extensional Tectonics and Stratigraphy of the North Atlantic Margins; Tankard, A., Balkwill, H., Eds.; AAPG Mem.; AAPG: Tulsa, OK, USA, 1989; Volume 46, pp. 341–361. [Google Scholar]
  86. Hiscott, R.N.; Wilson, R.; Gradstein, F.M.; Pujalte, V.; García-Mondéjar, J.; Boudreau, R.R.; Wishart, H.A. Comparative stratigraphy and subsidence history of Mesozoic rift basins of North Atlantic. AAPG Bull. 1990, 74, 60–76. [Google Scholar] [CrossRef]
  87. Pinheiro, L.; Wilson, R.; Reis, R.P.; Whitmarsh, R.; Ribeiro, A. The western Iberia margin, a geophysical and geological overview. Proc. ODP Sci. Results 1996, 149, 3–23. [Google Scholar]
  88. Rasmussen, E.S.; Lomholt, S.; Andersen, C.; Vejbæk, O.V. Aspects of the structural evolution of the Lusitanian Basin in Portugal and the shelf and slope area offshore Portugal. Tectonophys 1998, 300, 199–225. [Google Scholar] [CrossRef]
  89. Alves, T.M.; Gawthorpe, R.L.; Hunt, D.W.; Monteiro, J.H. Post-Jurassic tectono-sedimentary evolution of the Northern Lusitanian Basin (Western Iberian margin). Basin Res. 2003, 15, 227–250. [Google Scholar] [CrossRef]
  90. Alves, T.M.; Manuppella, G.; Gawthorpe, R.L.; Hunt, D.W.; Monteiro, J.H. The depositional evolution of diapir- and fault-bounded rift basins: Examples from the Lusitanian Basin of West Iberia. Sediment. Geol. 2003, 162, 273–303. [Google Scholar] [CrossRef]
  91. Alves, T.M.; Moita, C.; Sandnes, F.; Cunha, T.; Monteiro, J.H.; Pinheiro, L.M. Mesozoic–Cenozoic evolution of North Atlantic continental-slope basins: The Peniche basin, western Iberian margin. AAPG Bull. 2006, 90, 31–60. [Google Scholar] [CrossRef]
  92. Alves, T.M.; Moita, C.; Cunha, T.; Ullnaess, M.; Myklebust, R.; Monteiro, J.H.; Manuppella, G. Diachronous evolution of Late Jurassic–Cretaceous continental rifting in the northeast Atlantic (west Iberian margin). Tectonics 2009, 28, 1–32. [Google Scholar] [CrossRef]
  93. Dinis, P.A.; Dinis, J.L.; Tassinari, C.; Carter, A.; Callapez, P.M.; Morais, M. Detrital zircon geochronology of the Cretaceous succession from the Iberian Atlantic Margin, palaeogeographic implications. Int. J. Earth Sci. (Geol. Rundsch.) 2016, 105, 727–745. [Google Scholar] [CrossRef]
  94. Dinis, P.A.; Vermesch, P.; Callapez, P.M. Detrital zircon age signatures of the Mesozoic in the Lusitanian Basin and implications for the evolution of Iberia–Newfoundland conjugate margins. Terra Nova 2023, 35, 203–212. [Google Scholar] [CrossRef]
  95. Cunha, P.P. Estratigrafia e Sedimentologia dos Depósitos do Cretácico Superior e Terciário de Portugal Central, a Leste de Coimbra. Ph.D. Thesis, University of Coimbra, Coimbra, Portugal, 1982. [Google Scholar]
  96. Cunha, P.P.; Reis, R.P. Cretaceous sedimentary and tectonic evolution of the northern sector of the Lusitanian Basin (Portugal). Cretac. Res. 1995, 16, 155–170. [Google Scholar] [CrossRef]
  97. Callapez, P.M.; Barroso-Barcenilla, F.; Cambra-Moo, O.; Ortega, F.; Pérez-García, A.; Segura, M.; Torices, A. Fossil assemblages and palaeoenvironments in the Cenomanian vertebrate site of Nazaré (West Central Portugal). Neues Jahrb. Geol. Paläontol. Abh. 2014, 273, 179–195. [Google Scholar] [CrossRef]
  98. Santos, V.F.; Callapez, P.M.; Castanera, D.; Barroso-Barcenilla, F.; Rodrigues, N.P.C.; Cupeto, C.A. Dinosaur tracks from the Early Cretaceous of Parede tracksite (Cascais, Portugal): New implications on the sauropod palaeobiology of the Iberian Peninsula. J. Iber. Geol. 2015, 41, 155–166. [Google Scholar] [CrossRef]
  99. Berthou, P.Y. Albian-Turonian stage boundaries and subdivisions in the Western Portuguese Basin, with special emphasis on the Cenomanian–Turonian boundary in the Ammonite Facies and Rudist Facies. Bull. Geol. Soc. Den. 1984, 33, 41–45. [Google Scholar] [CrossRef]
  100. Berthou, P.Y. Zonation par les Ammonites du Cénomanien supérieur et du Turonien inférieur du Bassin Occidental Portugais. In Proceedings of the First Spanish Congress of Geology, Segovia, Spain, 14 April 1984; pp. 13–26. [Google Scholar]
  101. Segura, M.; Barroso-Barcenilla, F.; Callapez, P.M.; García-Hidalgo, J.F.; Gil, J. Depositional sequences and cephalopod assemblages in the upper Cenomanian—Lower Santonian of the Iberian Peninsula (Spain and Portugal). Geol. Acta 2014, 12, 19–27. [Google Scholar] [CrossRef]
  102. Hart, M.B.; Callapez, P.M.; Fisher, J.K.; Hannant, K.; Monteiro, J.F.; Price, G.D.; Watkinson, M.P. Micropalaeontology and stratigraphy of the Cenomanian/Turonian boundary in the Lusitanian Basin, Portugal. J. Iber. Geol. 2005, 31, 311–326. [Google Scholar]
  103. Choffat, P.L. Coup d’œil sur les mers mésozoiques du Portugal. Vierteljahrsschr. Naturforschenden Ges. Zür. 1896, 41, 294–317. [Google Scholar]
  104. Choffat, P.L. Sur le Crétacique de la région du Mondego. Comptes Rendus Acad. Sci. 1897, 124, 422–424. [Google Scholar]
  105. Choffat, P.L. Parallélisme entre le Crétacique du Mondego et celui de Lisbonne. Comptes Rendus Acad. Sci. 1897, 124, 519–521. [Google Scholar]
  106. Choffat, P.L. Faciès ammonitique et faciès récifal du Turonien Portugais. Bull. Soc. Géol. Fr. 1897, 25, 470–478. [Google Scholar]
  107. Berthou, P.Y.; Lauverjat, J. La limite Cénomano–Turonien. Essai de corrélation entre la série Portugaise à Vascoceras et les séries de l’Europe du Sud-Ouest et de l’Afrique du Nord. Comptes Rendus Acad. Sci. 1974, 278, 2605–2608. [Google Scholar]
  108. Berthou, P.Y.; Lauverjat, J. Le Cénomano–Turonien à Vascocératidés dans sa région type (embouchure du Rio Mondego, Beira Litoral, Portugal), corrélations avec le stratotype du Mans et d’autres séries téthysiennes. Newsl. Stratigr. 1975, 4, 96–118. [Google Scholar] [CrossRef]
  109. Berthou, P.Y.; Lauverjat, J. La limite Cénomano–Turonien dans les principaux faciès du bassin occidental Portugais. Comptes Rendus Acad. Sci. 1976, 282, 2143–2146. [Google Scholar]
  110. Soares, A.F. A “Formação Carbonatada” na região do Baixo Mondego. Comun. Serv. Geol. Port. 1980, 66, 99–109. [Google Scholar]
  111. Rocha, R.B.; Manupella, G.; Mouterde, R.; Ruget, C.; Zbyszewski, G. Carta Geológica de Portugal na Escala de 1:50 000. Notícia Explicativa da Folha 19C—Figueira da Foz; Serviços Geológicos de Portugal: Lisboa, Portugal, 1981; pp. 1–126. [Google Scholar]
  112. Soares, A.F.; Barbosa, B.P.; Reis, R.P. Esboço de enquadramento cronostratigráfico das unidades líticas pós-jurássicas da Orla Meso-Cenozóica Ocidental entre os paralelos de Pombal e Aveiro. Mem. Notíc. 1982, 93, 77–91. [Google Scholar]
  113. Soares, A.F.; Reis, R.P.; Daveau, S. Tentativa de correlação das unidades litostratigráficas da região do Baixo Mondego com as das bacias de Lousã e Arganil. Mem. Notíc. 1983, 96, 3–20. [Google Scholar]
  114. Barbosa, B.P.; Soares, A.F.; Rocha, R.B.; Manuppella, G.; Henriques, M.H. Carta Geológica de Portugal, Escala 1:50 000. Notícia Explicativa da Folha 19A—Cantanhede; Serviços Geológicos de Portugal: Lisboa, Portugal, 1988; pp. 1–46. [Google Scholar]
  115. Soares, A.F.; Marques, J.F.; Rocha, R.B. Contribuição para o conhecimento geológico de Coimbra. Mem. Notíc. 1985, 100, 41–72. [Google Scholar]
  116. Soares, A.F.; Lapa, M.; Marques, J.F. Contribuição para o conhecimento da litologia das unidades meso-cenozóicas da Bacia Lusitaniana a Norte do “acidente” da Nazaré (Sub-zona Setentrional). Mem. Notíc. 1986, 102, 23–41. [Google Scholar]
  117. Pimentel, R.J.; Audije-Gil, J.; Barroso-Barcenilla, F.; Berrocal-Casero, M.; Callapez, P.M.; Ozkaya de Juanas, S.; Segura, M. On the occurrence of Carentonosaurus Rage and Néraudeau, 2004 (Squamata, Pythonomorpha) in the Iberian Cretaceous, with description of a new species from the uppermost middle Cenomanian of West Portugal. Cretac. Res. 2023, 151, 105649. [Google Scholar] [CrossRef]
  118. Pimentel, R.J.; Barroso-Barcenilla, F.; Berrocal-Casero, M.; Callapez, P.M.; Ozkaya de Juanas, S.; Santos, V. On the occurrence of the Gar Obaichthys africanus Grande in the Cretaceous of Portugal: Palaeoecological and palaeobiogeographical implications. Geosciences 2023, 13, 372. [Google Scholar] [CrossRef]
  119. Berrocal-Casero, M.; Pimentel, R.; Callapez, P.M.; Barroso-Barcenilla, F.; Ozkaya de Juanas, S. On Segurasaurus (Squamata: Pythonomorpha), a new genus of lizard from the Cenomanian (Upper Cretaceous) of Portugal. Geosciences 2024, 14, 84. [Google Scholar] [CrossRef]
  120. Kennedy, W.J. Ammonite faunas and the “standard zones” of the Cenomanian to the Maastrichtian stages in their type areas, with some proposals for the definition of stage boundaries by ammonites. Bull. Geol. Soc. Den. 1984, 33, 147–161. [Google Scholar] [CrossRef]
  121. Kennedy, W.J. Integrated macrobiostratigraphy of the Albian to basal Santonian. Publ. Palaeontol. Inst. Univ. Upsala 1985, 5, 91–108. [Google Scholar]
  122. Kennedy, W.J. Ammonite biostratigraphy of the Albian to basal Santonian (Appendix 1). In Events of the Mid-Cretaceous; Reyment, R., Bengtson, P., Eds.; Pergamon Press: Oxford, UK, 1986; pp. 129–143. [Google Scholar]
  123. Bieler, R.; Mikkelsen, P.M. Bivalvia—A look at the branches. Zool. J. Linn. Soc. 2006, 148, 223–235. [Google Scholar] [CrossRef]
  124. Bouchet, P.; Rocroi, J.-P.; Bieler, R.; Carter, J.G.; Coan, E.V. Nomenclator of Bivalve Families with a Classification of Bivalve Families. Malacologia 2010, 52, 1–184. [Google Scholar]
  125. Bieler, R.; Mikkelsen, P.M.; Collins, T.M.; Glover, E.A.; González, V.L.; Graf, D.L.; Harper, E.M.; Healy, J.; Kawauchi, G.Y.; Sharma, P.P.; et al. Investigating the bivalve tree of life—An exemplar-based approach combining molecular and novel morphological characters. Invertebr. Syst. 2014, 28, 32–115. [Google Scholar] [CrossRef]
  126. Huber, M. Compendium of Bivalves. A Full-Colour Guide to 3,300 of the World’s Marine Bivalves. A Status on Bivalvia After 250 Years of Research; ConchBooks: Harxheim, Germany, 2010; pp. 1–901. [Google Scholar]
  127. Huber, M. Compendium of Bivalves 2. A Full-Colour Guide to the Remaining Seven Families. A Systematic Listing of 8,500 Bivalve Species and 10,500 Synonyms; ConchBooks: Harxheim. Germany, 2010; pp. 1–906. [Google Scholar]
  128. Carter, J.G.; Altaba, C.R.; Anderson, L.C.; Araujo, R.; Biakov, A.S.; Bogan, A.E.; Campbell, D.C.; Campbell, M.; Jin-hua, C.; Cope, J.C.W.; et al. A synoptical classification of the Bivalvia (Mollusca). Paleontol. Contrib. 2011, 4, 1–47. [Google Scholar] [CrossRef]
  129. WoRMS Editorial Board 2025. World Register of Marine Species. Available online: http://www.marinespecies.org (accessed on 17 November 2025).
  130. Newell, N.D. Classification of the Bivalvia. Am. Mus. Novit. 1965, 2206, 1–25. [Google Scholar]
  131. Moore, R.C. (Ed.) Treatise on Invertebrate Paleontology, Part N, Mollusca 6, Bivalvia; Geological Society of America and University of Kansas Press: Boulder, CO, USA, 1969; Volumes 1–3, pp. 1–490+491–952+953–1224. [Google Scholar]
  132. Waller, T.R. Morphology, morphoclines and a new classification of the Pteriomorphia (Mollusca: Bivalvia). Philos. Trans. R. Soc. Lond. B Biol. Sci. 1978, 284, 345–365. [Google Scholar] [CrossRef]
  133. Waller, T.R. New phylogenies of the Pectinidae (Mollusca: Bivalvia): Reconciling morphological and molecular approaches. In Scallops: Biology, Ecology and Aquaculture. Developments in Aquaculture and Fisheries Science, 35; Shumway, S.E., Parsons, G.J., Eds.; Elsevier: Amsterdam, The Netherlands, 2006; pp. 1–44. [Google Scholar]
  134. Linnaeus, C. Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, Cum Characteribus, Differentiis, Synonymis, Locis. Editio Decima, Reformata; Laurentii Salvii: Holmiae, Sweden, 1758. [Google Scholar]
  135. Beurlen, K. Beiträge zur Stammesgeschichte der Muscheln. Math.-Naturwissenschaftlichen Abt. Bayer. Akad. Wiss. München 1944, 1–2, 133–145. [Google Scholar]
  136. Gray, J.E. A revision of the genera of some of the families of conchifera or bivalve shells. Ann. Mag. Nat. Hist. Zool. Bot. Geol. Ser. 2 1854, 13, 408–418. [Google Scholar] [CrossRef]
  137. Teppner, W. Lamellibranchia Tertiaria, Anisomyaria II. In Fossilium Catalogus, I. Animalia, Pars 15; Diener, C., Ed.; W. Junk: Bberlin, Germany, 1922; pp. 67–296. [Google Scholar]
  138. Meek, F.B. Checklist of the invertebrate fossils of North America. Cretaceous and Jurassic. Smithson. Misc. Collect. 1864, 177, 1–40. [Google Scholar]
  139. Hall, J.; Meek, F.B. Descriptions of new species of fossils from the Cretaceous formations of Nebraska, with observations on Baculites ovatus and B. compressus, and the progressive development of the septa in Baculites, Ammonites and Scaphites. Mem. Am. Acad. Arts Sci. 1856, 5, 379–411. [Google Scholar] [CrossRef]
  140. Sowerby, J. The Mineral Conchology of Great Britain, or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells Which Have Been Preserved at Various Times and Depths in the Earth, vol. 3 (1818–1821); W. Arding: London, UK, 1818; Volume 2, pp. 1–251. [Google Scholar]
  141. Gabb, W.H. Synopsis of the Mollusca of the Cretaceous formations, including the geographical and stratigraphical range and synonymy. Proc. Am. Phil. Soc. 1861, 8, 150–245. [Google Scholar]
  142. Speden, I.G. Revision of Syncyclonema (Upper Cretaceous) and comparison with other small pectinid Bivalves and Entolium. Postilla 1967, 110, 1–36. [Google Scholar]
  143. Callapez, P.M.; Soares, A.F. A família Pectinidae (Mollusca, Bivalvia) no Cenomaniano-Turoniano do sector Norte da Orla Meso-Cenozóica Ocidental. Mem. Notíc. 1993, 115, 137–154. [Google Scholar]
  144. Sobetskiy, V.A. Paleobiological fades as exemplified by the Cenomanian Basin (southwestern Russian Platform). Int. Geol. Rev. 1967, 9, 713–722. [Google Scholar] [CrossRef]
  145. Nevesskaja, L.A. Morphogenesis and ecogenesis of Bivalves in the Phanerozoic. Paleontol. J. 2003, 37, 591–741. [Google Scholar]
  146. Nevesskaja, L.A. Ethological-trophic groups of bivalve mollusks and their distribution in the Phanerozoic. Paleontol. J. 2006, 40, 375–390. [Google Scholar] [CrossRef]
  147. Nevesskaja, L.A. Dynamics of taxonomic diversity of bivalves in the Phanerozoic. Paleontol. J. 2008, 42, 335–342. [Google Scholar] [CrossRef]
  148. Stephenson, L.W. The larger invertebrate fossils of the Navarro Group of Texas (Exclusive of Corals and Crustaceans and exclusive of the fauna of the Escondido Formation). Univ. Tex. Publ. 1941, 4101, 1–641. [Google Scholar]
  149. Stephenson, L.W. Larger invertebrate fossils of the Woodbine Formation (Cenomanian) of Texas. With Decapod crustaceans from the Woodbine Formation of Texas by H.B. Stenzel. USGS Prof. Pap. 1952, 242, 1–211. [Google Scholar]
  150. Anderson, F.M. Upper Cretaceous of the Pacific Coast. GSA Mem. 1958, 71, 1–378. [Google Scholar]
  151. Speden, I.G. The type Fox Hills Formation, Cretaceous (Maestrichtian), South Dakota. Part 2—Systematics of the Bivalvia. Bull. Peabody Mus. Nat. Hist. 1970, 33, 1–222. [Google Scholar]
  152. Woods, H. A Monograph of the Cretaceous Lamellibranchia of England, Part 4. Pectinidae; Palaeontographical Society: London, UK, 1902; pp. 145–196. [Google Scholar]
  153. Sobetskiy, V.A. K sistematike verkhnemelovykh pektinid srednego Prinestrovja [Contribution to the systematics of the Upper Cretaceous pectinids from the middle part of the Dniester River Basin]. Paleontol. Zhurn. 1960, 1960, 63–71. [Google Scholar]
  154. Skelton, P. Fluctuating sea-level. In The Cretaceous World; Skelton, P., Ed.; Cambridge University Press: Cambridge, UK, 2003; pp. 67–83. [Google Scholar]
  155. Callapez, P.M.; Barroso-Barcenilla, F.; Berrocal-Casero, M.; Cunha, P.P.; Dinis, P.A.; Lopes, F.C.; Ozkaya de Juanas, S.; Mendes, M.M.; Pimentel, R.J.; Santos, V.F.; et al. The Cretaceous post-rift series from the Portuguese onshore ranges of the West Iberian Margin and their history of research. In Cretaceous Project 200, Vol. 2: Regional Studies; Hart, M.B., Batenburg, S.J., Huber, B.T., Price, G.D., Thibault, N., Wagreich, M., Walaszczyk, I., Eds.; Special Publications of the Geological Society of London: London, UK, 2024; Volume 525. [Google Scholar]
  156. Stanley, S.M. Relation of shell form to life habits of the Bivalvia (Mollusca). Mem. Geol. Soc. Am. 1970, 125, 1–296. [Google Scholar]
  157. Stanley, M. Functional morphology and evolution of byssally attached bivalve mollusks. J. Paleontol. 1972, 46, 165–212. [Google Scholar]
  158. Vermeij, G.J. A Natural History of Shells; Princeton University Press: Princeton, NJ, USA, 1993; pp. 1–207. [Google Scholar]
  159. Dame, R.F. Ecology of Marine Bivalves. An Ecosystem Approach, 2nd. ed.; CRC Press: Boca Raton, FL, USA, 2012; pp. 1–271. [Google Scholar]
  160. Shumway, E.S.; Parsons, G.J. (Eds.) Scallops: Biology, Ecology and Aquaculture, 3rd ed.; Developments in Aquaculture and Fisheries Science, 40; Elsevier: Amsterdam, The Netherlands, 2016; pp. 1–1196. [Google Scholar]
  161. Berthou, P.Y. Répartition stratigraphique actualisée des principaux foraminifères benthiques du Crétacé moyen et supérieur du Bassin Occidental Portugais. Benthos 1984, 83, 45–54. [Google Scholar]
  162. Bishop, G.A. Occurrence and fossilization of the Dakoticancer assemblage, Upper Cretaceous Pierre Shale, South Dakota. In Communities of the Past; Gray, J., Boucot, A.J., Berry, W.B.N., Eds.; Hutchinson Ross Publishing Company: Stroudsburg, PA, USA, 1992; pp. 383–413. [Google Scholar]
  163. Morton, B. The biology and functional morphology of Fragum erugatum (Bivalvia: Cardiidae) from Shark Bay, Western Australia: The significance of its relationship with entrained zooxanthellae. J. Zool. 2000, 251, 39–52. [Google Scholar] [CrossRef]
  164. Sokolnikova, Y. Endobiotic microalgae in molluscan life. Fish. Aquat. Sci. 2022, 25, 499–516. [Google Scholar] [CrossRef]
  165. O’Connor, N.; Crowe, T.; Mcgrath, D. Effects of epibiotic algae on the survival, biomass and recruitment of mussels, Mytilus L. (Bivalvia: Mollusca). J. Exp. Mar. Biol. Ecol. 2006, 328, 265–276. [Google Scholar] [CrossRef]
  166. Vázquez, N.; Rodríguez, F.; Ituarte, C.; Klaich, J.; Cremonte, F. Host–parasite relationship of the geoduck Panopea abbreviata and the green alga Coccomyxa parasitica in the Argentinean Patagonian coast. J. Invertebr. Pathol. 2010, 105, 254–260. [Google Scholar] [CrossRef]
  167. Mies, M.; Sumida, P.Y.G.; Rädecker, N.; Voolstra, C.R. Marine invertebrate larvae associated with Symbiodinium: A mutualism from the start? Front. Ecol. Evol. 2017, 5, 56. [Google Scholar] [CrossRef]
  168. Katherine, A.B.; Hillman, J.R.; Jeffs, A.G. Macroalgae and conspecifics serve as critical attachment substrates for juvenile green-lipped mussels (Perna canaliculus) during different stages of development. J. Exp. Mar. Biol. Ecol. 2025, 588, 152108. [Google Scholar] [CrossRef]
  169. Harvey, M.; Bourget, E.; Miron, G. Settlement of Iceland scallop Chlamys islandica spat in response to hydroids and filamentous red algae: Field observation and laboratory experiments. Mar. Ecol. Prog. Ser. 1993, 99, 283–292. [Google Scholar] [CrossRef]
  170. Mendo, T.; Lyle, J.M.; Moltschaniwskyj, N.A.; Semmens, J.M. Early post-settlement mortality of the scallop Pecten fumatus and the role of algal mats as a refuge from predation. ICES J. Mar. Sci. 2015, 72, 2322–2331. [Google Scholar] [CrossRef]
  171. Pohle, D.G.; Bricelj, V.M.; Garcia-Esquivel, Z. The eelgrass canopy: An above-bottom refuge from benthic predators for juvenile bay scallops Argopecten irradians. Mar. Ecol. Prog. Ser. 1991, 74, 47–59. [Google Scholar] [CrossRef]
  172. Minchin, D. Biological observations on young scallops, Pecten maximus. J. Mar. Biol. Assoc. UK 1992, 72, 807–819. [Google Scholar] [CrossRef]
  173. Kamenos, N.A.; Moore, P.G.; Hall-Spencer, J.M. Attachment of the juvenile queen scallop (Aequipecten opercularis (L.)) to maerl in mesocosm conditions; juvenile habitat selection. J. Exp. Mar. Biol. Ecol. 2004, 306, 139–155. [Google Scholar] [CrossRef]
  174. Tettelbach, S.; Smith, C.; Weinstock, A.; Bonal, D.; Peterson, B.; Carroll, J. Comparative survival of bay scallops in eelgrass and the introduced alga, Codium fragile, in a New York estuary. Mar. Biol. 2010, 157, 249–259. [Google Scholar] [CrossRef]
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Figure 1. Location and geological context of the studied area. (a)—General location in the Iberian Peninsula (red box). (b)—Location in the Baixo Mondego region of West Portugal (red box). (c)—Overview of the studied area in the eastern ranges of Baixo Mondego, showing the main localities (black circles) and the geological mapping of the Cenomanian–Turonian Trouxemil Fm. (green areas), with indication of the stratigraphic sections with carbonate and mixed facies with Syncyclonema goyi sp. nov. (red stars). 1—Lapa, 2—Mala, 3—Marmeleira do Botão, 4—Pisão, 5—Barcouço, 6—Sargento-Mor, 7—Salgueirosa (Trouxemil), 8—Adões, 9—Senhora das Neves, 10—Rios Frios, 11—Quinta do Belregão, 12—Espigão 1, 13—Cioga do Monte, 14—Espigão 2, 15—Fonte da Areia (Ançã), 16—Geria, 17—Antanhol, 18—Condeixa-a-Nova. (d)—Upper member of the Trouxemil Fm. (upper Cenomanian units with facies of nodular marly limestone) in the section of Fonte da Areia (Ançã), the type locality of Syncyclonema goyi sp. nov. (e)—Lower part of the same section (basal upper Cenomanian units with facies of sandy marl and nodular marly limestones and massive whitish limestone).
Figure 1. Location and geological context of the studied area. (a)—General location in the Iberian Peninsula (red box). (b)—Location in the Baixo Mondego region of West Portugal (red box). (c)—Overview of the studied area in the eastern ranges of Baixo Mondego, showing the main localities (black circles) and the geological mapping of the Cenomanian–Turonian Trouxemil Fm. (green areas), with indication of the stratigraphic sections with carbonate and mixed facies with Syncyclonema goyi sp. nov. (red stars). 1—Lapa, 2—Mala, 3—Marmeleira do Botão, 4—Pisão, 5—Barcouço, 6—Sargento-Mor, 7—Salgueirosa (Trouxemil), 8—Adões, 9—Senhora das Neves, 10—Rios Frios, 11—Quinta do Belregão, 12—Espigão 1, 13—Cioga do Monte, 14—Espigão 2, 15—Fonte da Areia (Ançã), 16—Geria, 17—Antanhol, 18—Condeixa-a-Nova. (d)—Upper member of the Trouxemil Fm. (upper Cenomanian units with facies of nodular marly limestone) in the section of Fonte da Areia (Ançã), the type locality of Syncyclonema goyi sp. nov. (e)—Lower part of the same section (basal upper Cenomanian units with facies of sandy marl and nodular marly limestones and massive whitish limestone).
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Figure 2. Stratigraphic section of Fonte da Areia, Ançã (West Portugal), the type locality for Syncyclonema goyi sp. nov., showing the upper Cenomanian inner shelf units of the Trouxemil Fm., comprising carbonate and mixed carbonate–siliciclastic facies rich in invertebrate assemblages. The red asterisk marks the stratigraphic position of the holotype of Syncyclonema goyi sp. nov. described herein.
Figure 2. Stratigraphic section of Fonte da Areia, Ançã (West Portugal), the type locality for Syncyclonema goyi sp. nov., showing the upper Cenomanian inner shelf units of the Trouxemil Fm., comprising carbonate and mixed carbonate–siliciclastic facies rich in invertebrate assemblages. The red asterisk marks the stratigraphic position of the holotype of Syncyclonema goyi sp. nov. described herein.
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Figure 3. Syncyclonema goyi sp. nov. (Callapez, Barroso-Barcenilla, Berrocal-Casero, and Pimentel) from the upper Cenomanian of West Portugal. (a–d) Holotype, left valve, with the shell layers and internal microstructure preserved, (a) detail of the anterior auricle, (b) general view, (c) detail of the posterior auricle, (d) detail of the sculpture with nearly 90 very small, uniform radial striae; DCTUC-FA8-BR100. (e,f) Paratype, right valve, with the shell layers and internal microstructure partly preserved, (e) general view, (f) detail of the sculpture in the ventral side of the disc; DCTUC-FA9-BR54. (g,h) Paratype, right valve, with the shell compressed and recrystallized, (g) general view, (h) detail of the anterior auricle; DCTUC-CX16. (i,j) Paratype, right valve, with internal mould and the shell compressed and recrystallized, (i) general view, (f) detail of the anterior auricle; DCTUC-CX34. Localities: (a–f) Fonte da Areia, Ançã; (g–j) Condeixa-a-Nova.
Figure 3. Syncyclonema goyi sp. nov. (Callapez, Barroso-Barcenilla, Berrocal-Casero, and Pimentel) from the upper Cenomanian of West Portugal. (a–d) Holotype, left valve, with the shell layers and internal microstructure preserved, (a) detail of the anterior auricle, (b) general view, (c) detail of the posterior auricle, (d) detail of the sculpture with nearly 90 very small, uniform radial striae; DCTUC-FA8-BR100. (e,f) Paratype, right valve, with the shell layers and internal microstructure partly preserved, (e) general view, (f) detail of the sculpture in the ventral side of the disc; DCTUC-FA9-BR54. (g,h) Paratype, right valve, with the shell compressed and recrystallized, (g) general view, (h) detail of the anterior auricle; DCTUC-CX16. (i,j) Paratype, right valve, with internal mould and the shell compressed and recrystallized, (i) general view, (f) detail of the anterior auricle; DCTUC-CX34. Localities: (a–f) Fonte da Areia, Ançã; (g–j) Condeixa-a-Nova.
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Figure 4. Paratypes of Syncyclonema goyi sp. nov. (Callapez, Barroso-Barcenilla, Berrocal-Casero, and Pimentel) from the upper Cenomanian of West Portugal. (a) Left valve (LV); DCTUC-CX40. (b) LV; DCTUC-CX14. (c) Right valve (RV); 5062. (d) LV; DCTUC-QB48-BR106. (e) LV; DCTUC-QB48-BR107. (f) RV; DCTUC-RF7. (g) RV; DCTUC-QB55-BR108. (h) LV; DCTUC-E34-BR112. (i) LV; DCTUC-CX20. (j) RV; DCTUC-A8-BR53. (k) RV; DCTUC-CX22. (l) RV; DCTUC-CX37. (m) LV; DCTUC-E34-BR111. (n) LV; DCTUC-QB55-BR113. (o) LV; DCTUC-QB55-BR109. (p) RV; DCTUC-QB55-BR110a-b. Localities: (a,b) Condeixa-a-Nova; (c) Espigão 2; (d,e) Quinta do Belregão; (f) Rios Frios; (g) Quinta do Belregão; (h) Espigão; (i) Condeixa-a-Nova; (j) Antanhol; (k,l) Condeixa-a-Nova; (m) Espigão; (n–p) Quinta do Belregão.
Figure 4. Paratypes of Syncyclonema goyi sp. nov. (Callapez, Barroso-Barcenilla, Berrocal-Casero, and Pimentel) from the upper Cenomanian of West Portugal. (a) Left valve (LV); DCTUC-CX40. (b) LV; DCTUC-CX14. (c) Right valve (RV); 5062. (d) LV; DCTUC-QB48-BR106. (e) LV; DCTUC-QB48-BR107. (f) RV; DCTUC-RF7. (g) RV; DCTUC-QB55-BR108. (h) LV; DCTUC-E34-BR112. (i) LV; DCTUC-CX20. (j) RV; DCTUC-A8-BR53. (k) RV; DCTUC-CX22. (l) RV; DCTUC-CX37. (m) LV; DCTUC-E34-BR111. (n) LV; DCTUC-QB55-BR113. (o) LV; DCTUC-QB55-BR109. (p) RV; DCTUC-QB55-BR110a-b. Localities: (a,b) Condeixa-a-Nova; (c) Espigão 2; (d,e) Quinta do Belregão; (f) Rios Frios; (g) Quinta do Belregão; (h) Espigão; (i) Condeixa-a-Nova; (j) Antanhol; (k,l) Condeixa-a-Nova; (m) Espigão; (n–p) Quinta do Belregão.
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Figure 5. Block diagram depicting the palaeoenvironment and marine invertebrates associated with Syncyclonema goyi sp. nov. in the upper Cenomanian of the West Portuguese Carbonate Platform, in the eastern ranges of the Baixo Mondego region, near Coimbra, West Central Portugal. 1—Serpulid worms, 2—Syncyclonema goyi sp. nov., 3—Decapod crustaceans, 4—Tylostoma ovatum, 5—Rhynchostreon suborbiculatum, 6—Aporrhais costae. Algae morphology and represented colours are hypothetical.
Figure 5. Block diagram depicting the palaeoenvironment and marine invertebrates associated with Syncyclonema goyi sp. nov. in the upper Cenomanian of the West Portuguese Carbonate Platform, in the eastern ranges of the Baixo Mondego region, near Coimbra, West Central Portugal. 1—Serpulid worms, 2—Syncyclonema goyi sp. nov., 3—Decapod crustaceans, 4—Tylostoma ovatum, 5—Rhynchostreon suborbiculatum, 6—Aporrhais costae. Algae morphology and represented colours are hypothetical.
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Table 1. Dimensions of the holotype and paratypes (mm).
Table 1. Dimensions of the holotype and paratypes (mm).
SpecimenUPDLWAA
LV—Holotype (DCTUC-FA8-BR100)7.86.91.2104°
RV—Paratype (DCTUC-QB48-BR108)8.8-1.4102°
RV—Paratype (DCTUC-CX16)6.25.9-101°
RV—Paratype (DCTUC-CX34)8.38.4-97°
LV—Paratype (DCTUC--CX40)9.69.0-101°
LV—Paratype (DCTUC- CX14)9.48.6-90°
RV—Paratype (5062)9.28.51.293°
LV—Paratype (DCTUC- QB48-BR106)8.4-1.3-
LV—Paratype (DCTUC- QB48-BR107)8.47.41.490°
RV—Paratype (DCTUC-RF7)9.68.8-97°
RV—Paratype (DCTUC- QB55-BR108)8.98.31.5108°
LV—Paratype (DCTUC- E34-BR112)9.18.91.496°
LV—Paratype (DCTUC-CX20)9.68.6-96°
RV—Paratype (DCTUC- A8-BR53)8.48.31.094°
RV—Paratype (DCTUC-CX22)9.18.0-94°
RV—Paratype (DCTUC-CX37)10.09.6-99°
LV—Paratype (DCTUC- E34-BR111)10.08.61.596°
LV—Paratype (DCTUC- QB55-BR113)8.87.91.491°
LV—Paratype (DCTUC- QB55-BR109)7.97.40.792°
RV—Paratype (DCTUC- QB55-BR110b)4.33.80.497°
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MDPI and ACS Style

Callapez, P.M.; Barroso-Barcenilla, F.; Berrocal-Casero, M.; Brandão, J.M.; Comas-Rengifo, M.J.; Domingos, R.; Gomes, E.; Lopes, F.C.; Mendes, M.M.; Ozkaya de Juanas, S.; et al. A New Scallop Species, Syncyclonema goyi sp. nov. (Bivalvia, Pectinida, Entoliidae), from the Upper Cenomanian of West Portugal. Geosciences 2026, 16, 94. https://doi.org/10.3390/geosciences16030094

AMA Style

Callapez PM, Barroso-Barcenilla F, Berrocal-Casero M, Brandão JM, Comas-Rengifo MJ, Domingos R, Gomes E, Lopes FC, Mendes MM, Ozkaya de Juanas S, et al. A New Scallop Species, Syncyclonema goyi sp. nov. (Bivalvia, Pectinida, Entoliidae), from the Upper Cenomanian of West Portugal. Geosciences. 2026; 16(3):94. https://doi.org/10.3390/geosciences16030094

Chicago/Turabian Style

Callapez, Pedro Miguel, Fernando Barroso-Barcenilla, Melani Berrocal-Casero, José Manuel Brandão, Maria José Comas-Rengifo, Rúben Domingos, Elsa Gomes, Fernando Carlos Lopes, Mário Miguel Mendes, Senay Ozkaya de Juanas, and et al. 2026. "A New Scallop Species, Syncyclonema goyi sp. nov. (Bivalvia, Pectinida, Entoliidae), from the Upper Cenomanian of West Portugal" Geosciences 16, no. 3: 94. https://doi.org/10.3390/geosciences16030094

APA Style

Callapez, P. M., Barroso-Barcenilla, F., Berrocal-Casero, M., Brandão, J. M., Comas-Rengifo, M. J., Domingos, R., Gomes, E., Lopes, F. C., Mendes, M. M., Ozkaya de Juanas, S., Pereira, H. J., Perez-Cano, J., Pimentel, R. J., Santos, V. F. d., & Segura, M. (2026). A New Scallop Species, Syncyclonema goyi sp. nov. (Bivalvia, Pectinida, Entoliidae), from the Upper Cenomanian of West Portugal. Geosciences, 16(3), 94. https://doi.org/10.3390/geosciences16030094

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