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| Platypterygius elsuntuoso Páramo-Fonseca, Benavides-Cabra & Garavito-Camacho, 2024 |
Abstract
In this paper, we describe a new ophthalmosaurid specimen found in the lower Barremian beds of the Paja Formation at Villa de Leiva, Boyacá, Colombia. The specimen represents a new species of Platypterygius, P. elsuntuoso sp. nov. defined by three unique features within the genus: a small ventral peg in the anterior ventral border of the extracondylar area of the basioccipital; a supratemporal groove in the quadrate; and a shallow neck at the base of the acellular cementum ring on the teeth root. In support of our taxonomic determination, in this contribution we also assess the species composition of the genus Platypterygius, comparing the known anatomy of the type species P. platydactylus with that of the other species previously assigned to the genus. We found that a great morphological affinity in the forelimb of the species P. americanus, P. australis, P. hercynicus, and P. sachicarum (lower Barremian to lower Cenomanian) with that of the type species (Aptian) is unquestionable and differentiate them from all other ophthalmosaurids. Three new diagnostic features (synapomorphies of the genus) support their inclusion in Platypterygius. Consequently, the genus name “Kyhytysuka”, recently proposed to differentiate P. sachicarum from the genus Platypterygius is here rejected. A careful comparison of the cranial characteristics of Platypterygius specimens preserving associated cranial and fin remains demonstrate that Platypterygius is a genus distinguishable from other ophthalmosaurids not only by a typical forelimb but also by a particular combination of skull features. In this context, the skull morphology of “Simbirskiasaurus” concurs with that defining Platypterygius and its minor differences are not sufficient to support its generic distinction. The morphological comparisons and our phylogenetic analysis show the new species P. elsuntuoso more closely related to the Colombian species P. sachicarum than to other species of Platypterygius. Given that the new species came from the lower Barremian and P. sachicarum came from the upper Barremian, the minor differences in dentition found between the two species suggest a speciation by adaptation to new food sources in the Cretaceous epicontinental sea of Colombia.
Keywords: Ophthalmosauridae; Platypterygius; Barremian; Colombia
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| Platypterygius elsuntuoso sp. nov., holotype FCG-CBP-28. Photographs and interpretative drawings of the specimen in A, right lateral view, B, left lateral view before extracting the basioccipital and the left coracoid, and C, dorsal view. Grey: sediment; black: breakage space; dots: missing surface. Abbreviations: aen, anterior external narial aperture; an, angular; ar, articular; at, atlas; ax, axis; bo, basioccipital; bs, basisphenoid; d, dentary; es, sclerotic plates; f, frontal; fj, facet for the jugal; hy, hyoid; j, jugal; la, lacrimal; lan, left angular; lar, left articular; lcor, left coracoid; ld, left dentary; ln, left nasal; lpt, left pterygoid; lsa, left surangular; lsp, left splenial; mx, maxilla; n, nasal; np, nasal process; ns, neural spine; oe, occipital element; p, parietal; pal, palatine; par, prearticular; pf, parietal foramen; ph, phalange; pmx, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; ps, parasphenoid; pt, pterygoid; q, quadrate; qj, quadratojugal; rb, rib; rar, right articular; rn, right nasal; rpar, right prearticular; rpt, right pterygoid; rst, right supratemporal; rstp, right stapes; sa, surangular; saf, surangular fossa; sp, splenial; st, supratemporal; sym, posterior end of the symphysis; v, vomer; vc, vertebral centrum. Scale bars = 100 mm. |
ICHTHYOSAURIA de Blainville, 1835
OPHTHALMOSAURIDAE Baur, 1887
Platypterygius elsuntuoso sp. nov.
Holotype and only known specimen: FCG-CBP-28. A skull lacking the anterior portion of the snout; some disarticulated axial elements, incomplete left coracoid, and a few phalanges.
Type locality and horizon: Loma La Cabrera, northwest of Villa de Leiva, Boyacá. Paja Formation, Arcillolitas abigarradas Member, segment A or B of Etayo-Serna (1968a), lower Barremian (Benavides-Cabra et al., 2023) (Fig. 1).
Diagnosis: P. elsuntuoso is distinguished from other species of Platypterygius by the following unique features: 1- The anterior ventral border of the extracondylar area of the basioccipital bears a small ventral peg anteroventrally directed (Shared with Plutoniosaurus, Zverkov pers. comm.), which fits into a posteroventral depression found in the basisphenoid; 2- Quadrate with supratemporal groove dorsal to the stapedial foramen (Shared with Plutoniosaurus Zverkov pers. comm.; and Undorosaurus see Zverkov & Efimov, 2019) ; and 3- Root of teeth with a shallow neck at the base of the acellular cementum ring.
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Derivation of name: from “el suntuoso”, Spanish for “the sumptuous”, nickname used by C. B. Padilla, deceased founder of the FCG and CIP, when referring to the specimen.
María E. Páramo-Fonseca, Cristian D. Benavides-Cabra and Renzo A. Garavito-Camacho. 2024. A New Species of Platypterygius (Ophthalmosauridae) from the lower Barremian of Colombia and Assessment of the Species Composition of the Genus. Earth Sciences Research Journal. 28(2); DOI: doi.org/10.15446/esrj.v28n2.112332