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| Ophiussasuchus paimogonectes López-Rojas, Mateus, Marinheiro, Mateus, & Puértolas-Pascual, 2024 DOI: 10.26879/1316 |
ABSTRACT
Plenty of goniopholidid species from the Mesozoic have been found in the Iberian Peninsula. A previous goniopholidid taxon, Goniopholis baryglyphaeus Schwarz, 2002, from the Late Jurassic of the Guimarota coal mine (Leiria, central Portugal) was described. This taxon corresponds to a partial skull and some postcranial material, and it marked the oldest and first ever record of goniopholidid and Goniopholis species described for the Iberian Peninsula. Here we present a well-preserved, almost complete, skull of a new species, Ophiussasuchus paimogonectes gen. et sp. nov. from Upper Jurassic deposits of Praia de Paimogo (near Lourinhã, central west Portugal). The specimen corresponds to a mesorostrine, platyrostral skull of a medium-sized goniopholidid coming from the upper Kimmeridgian within the Lourinhã Formation. Phylogenetically, the new species is recovered as the sister taxon of the Early Cretaceous European clade made by Hulkepholis and Anteophthalmosuchus. Although its position is well-resolved, this new taxon displays intermediate morphological traits, sharing characteristics with Jurassic Asian and American basal goniopholidids (e.g., presence but lesser development of the secondary choana with the nasopharyngeal duct partially open), as well as more derived characters shared with Cretaceous European taxa such as Hulkepholis (e.g., the shape of the supratemporal fenestra and the palatines). As a result, Ophiussasuchus paimogonectes gen. et sp. nov. exhibits characteristics suggesting a reversion to primitive goniopholidid conditions or intermediate states between the goniopholidid taxa of North America and Europe. These findings support the shared Late Jurassic fauna between the Morrison and Lourinhã Formations, while also having high endemism of taxa.
Keywords: new genus; new species; Lourinhã Formation; upper Kimmeridgian; Crocodylomorpha; phylogeny
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| Skull of ML2776 Ophiussasuchus paimogonectes gen. et sp. nov. Anatomical abbreviations: f, frontal; itf, infratemporal fenestra; j, jugal; lac, lacrimal; mx, maxilla; mx.dp, maxillary depressions; n, nasal; o, orbit; pa, parietal; pal, palpebral; pf, prefrontal; pmx, premaxilla; po, postorbital; q, quadrate; qj, quadratojugal; sq, squamosal; stf, supratemporal fenestra; t, tooth. Scale represents 10 cm. |
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| Skull of ML2776 Ophiussasuchus paimogonectes gen. et sp. nov., in lateral view. Anatomical abbreviations: ec, ectopterygoid; j, jugal; mx, maxilla; mx.dp, maxillary depressions; n, nasal; pal, palpebral; pf, prefrontal; pmx, premaxilla; po, postorbital; pt, pterygoid; q, quadrate; qj, quadratojugal; sq, squamosal; t, tooth. Scale represents 10 cm. |
SYSTEMATIC PALEONTOLOGY
Superorder CROCODYLOMORPHA Hay, 1930 (sensu Walker, 1970)
Clade CROCODYLIFORMES Hay, 1930
Suborder MESOEUCROCODYLIA Whetstone and Whybrow, 1983 (sensu Benton and Clark, 1988)
Infraoder NEOSUCHIA Gervais, 1871 (sensu Benton and Clark, 1988)
Family GONIOPHOLIDIDAE Cope, 1875
Genus OPHIUSSASUCHUS gen. nov.
Etymology. ‘ Ophiussa ’ refers to the ancient name given by the Greeks to the area where is now Portugal; and ‘ suchus ’ is from the Greek souchos that refers to crocodile-headed Egyptian god Sobek.
OPHIUSSASUCHUS PAIMOGONECTES sp. nov
Holotype. ML2776, an almost complete and well-preserved isolated skull, with some teeth still attached. The specimen is deposited at Lourinhã Museum (Museu da Lourinhã), Lourinhã, Portugal.
Etymology. ‘paimogonectes’ refers to the one who swims in Paimogo, where the specimen was found (Paimogo beach, Lourinhã, Portugal).
Age and horizon. Praia Azul Member, Lourinhã Formation, Lusitanian Basin, west coast of Portugal. upper Kimmeridgian-lower Tithonian, Upper Jurassic.
Type locality. Praia de Paimogo (GPS coordinates: 39° 17’ 10.4” N, 9° 20 ’17.4” W), Lourinhã, Lisbon, Portugal.
Diagnosis. Medium-sized crocodylomorph about 2.5 m to 3 m long (estimated body length based on Young et al., 2011), with platyrostral, mesorostrine skull and a marked festooned contour which differs from other goniopholidids since it possess a less pronounced axe-shaped premaxillae dorsal outline; smooth perinarial region with absence of crests around it; presence of different number of maxillary depressions between the left and right regions (four and five, respectively); anteriorly well-marked V-shape border of the palatines in contact with the maxillae; nasals with straight, sub-parallel margins between the maxillae, with little to no lateral expansion at their posterior-most border; main body of the frontal with sub-squared shape in dorsal view, without lateral expansion; nasopharyngeal duct less ventrally exposed than in Jurassic taxa (e.g., Calsoyasuchus or Eutretauranosuchus) but not as closed as in Cretaceous taxa (e.g., Hulkepholis or Anteophthalmosuchus); presence of two small, thin, anteroposteriorly elongated and crescent-shaped palatal fenestrae between the maxillae and the palatines.
CONCLUSIONS:
A new and the most complete skull of crocodylomorph (ML2776) from the Late Jurassic of Lourinhã Fm, was recovered and is here described as a new genus and species, Ophiussasuchus paimogonectes gen. et sp. nov.
This new taxon was recovered with a unique combination of 15 synapomorphies. These synapomorphies are a combination of features from both older North American and younger European taxa, such as the shape of the rostrum with a less-projected axe shape compared with Jurassic North American species (Amphicotylus) and more similar to Cretaceous taxa, while the nasopharyngeal duct openings are more closed than older species (Calsoyasuchus or Eutretauranosuchus) but not completely closed as in Hulkepholis and Anteophthalmosuchus, with which Ophiussasuchus paimogonectes gen. et sp. nov. has closer relationships. In addition, ML2776 displays an asymmetrical number of maxillary fossae (four in the left region while five in the right region). However, any hypothesis regarding this asymmetry cannot be contrasted until more specimens are found.
The new taxon Ophiussasuchus paimogonectes gen. et sp. nov. increases the already high paleodiversity of crocodylomorphs of the locality. It also supports the hypothesis of a shared fauna between North America (Morrison Fm) and Western Europe (Lourinhã Fm) during the Late Jurassic, as well as the high endemism of Portugal, distinguishing both continents.
Víctor López-Rojas, Simão Mateus, João Marinheiro, Octávio Mateus, and Eduardo Puértolas-Pascual. 2024. A New goniopholidid Crocodylomorph from the Late Jurassic of Portugal. Palaeontologia Electronica, 27(1):a5. DOI: 10.26879/1316
