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| Ogresuchus furatus Sellés, Blanco, Vila, Marmi, López-Soriano, Llácer, Frigola, Canals & Galobart, 2020 |
Abstract
Sebecosuchia was a group of highly specialized cursorial crocodyliforms that diversified during the Cretaceous and persist until the end of the Miocene. Their unique combination of cranial and post-cranial features indicates that they were active terrestrial predators that occupied the apex of the Late Cretaceous terrestrial ecosystems, even competing with theropod dinosaurs. Here, we report the discovery of the earliest sebecid worldwide, and the first from Eurasia, Ogresuchus furatus gen. et sp. nov., based on a semi-articulate specimen located in a titanosaurian sauropod nesting ground. The new taxon challenges current biogeographical models about the early dispersal and radiation of sebecid crocodylomorphs, and suggests an origin of the group much earlier than previously expected. Moreover, the new taxon suggests a potential convergent evolution between linages geographically isolated. Taphonomic evidences suggest that Ogresuchus died almost in the same place where fossilized, in a dinosaur nesting area. Biometric and morphologic observations lead to speculate that Ogresuchus could easily predate on sauropod hatchlings.
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| Figure 1: Skeletal remains of of Ogresuchus furatus (MCD-7149). (A,C) Photographic and (B,D) interpretative draws of the postcranial (A,B) and cranial (C,D) elements, and (E) silhouette showing preserved elements of Ogresuchus furatus. cv caudal vertebra, dv dorsal vertebra, fe femur, gr groves, lul left ulna, lt left tibia, m1-4 maxillary tooth, mc metacarpal, nvf neuro-vascular foramens, r rib, rt right tibia, sa sacral. Scale bar = 1 cm for (C,D) and 10 cm for (E). |
Systematic palaeontology
Crocodylomorpha Walker, 1970 (sensu Clark, 1986).
Crocodyliformes Hay, 1930 (sensu Clark, 1986).
Mesoeucrocodylia Whetstone and Whybrow, 1983.
Notosuchia Gasparini, 1971.
Sebecosuchia Simpson, 1937.
Sebecidae Simpson, 1937.
Ogresuchus furatus gen. et sp. nov.
Diagnosis: Small-sized sebecid diagnosed by the following autapomorphies: five maxillary tooth positions; teeth with smooth (unserrated) carinae; presence of apicobasal ridges on the enamel of the incisiviform and caniniform teeth; presence of apicobasal ridges on the enamel of posterior teeth; large and aligned neurovascular foramina on lateral surface of the maxilla; foramen in perinarial depression of the premaxilla; very large incisive foramen; absence of a large nutrient foramen on palatal surface of the premaxilla-maxilla contact; palatal surface of the maxilla without rugose surface; nasal-maxilary contacts remain parallel to each other (do not converge anteriorly or posteriorly); postzygapophyses located dorsally to the transverse processes in dorsal vertebrae.
Etymology: Genus name after Ogre- (French), in reference to the inferred feeding behaviour that included infant individuals, like the mythological creature from European folk tales; and –suchus, from the Greek Souchos meaning crocodile. Species name after furatus, from the Latin furari meaning to be stolen, in reference to the unfortunate event that took place during the fieldworks (see Supplementary Information S1).
Holotype: MCD-7149 (Museu de la Conca Dellà), a semi-articulate skeleton preserving the anterior part of the rostrum and several axial and appendicular elements (Fig. 1), and nine associate blocks containing large dinosaur eggshell fragments.
Type locality and horizon: El Mirador site, (Coll de Nargó area, Lleida Province, Catalonia). High cemented grey marl level from the “lower grey unit” of the Tremp Formation; early Maastrichtian (near the C32n-C31r chrone boundary).
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| Figure 2: 3D reconstruction of the skull of Ogresuchus furatus (MCD-7149) in (a) lateral, (b) medial, (c) dorsal, (d) palatal, and (e) cranial view. (f) Volume rendering of the segmented neurovascular network of the trigeminal nerve overlaid on the articulated premaxilla and maxilla. app anterior palpebral, ch choana, dn dentary notch, en external naris, f neuro-vascular foramen, if inferior foramen, l-mx lacrimal-maxilla contact, m1-5 maxillary tooth, mes medial shelf, mx maxilla, paf palatal foramen, pd paramedian depressions, pfr prefrontal, plt palatine, pltf palatine foramen, pm1-4 premaxillary tooth, pmx premaxilla, pmx-mx premaxilla-maxilla contact, poas posantral strut, s apicobasal sulcus, snv-tgn V supranarial vessels and the trigeminal nerve V (ophthalmic branch), mv-tgn V maxillary vessels and the trigeminal nerve V (maxillary branch). Scale bar = 2 cm. |
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| Figure 3: Time-calibrated evolutionary tree for Sebecosuchia. Reduced Consensus tree produced in TNT, with additional sebecosuchia taxa incorporated (see Supplementary text). The circles at each node represent the relative probabilities for the ancestral areas inferred using the Statistic Divergence-Vicariance Analysis method (S-DIVA; see Supplementary text). Global paleogeographic reconstructions from the Paleobiology Database (https://www.paleobiodb.org). |
Albert G. Sellés, Alejandro Blanco, Bernat Vila, Josep Marmi, Francisco J. López-Soriano, Sergio Llácer, Jaime Frigola, Miquel Canals and Àngel Galobart. 2020. A Small Cretaceous Crocodyliform in A Dinosaur Nesting Ground and the Origin of Sebecids. Scientific Reports. 10, 15293. DOI: 10.1038/s41598-020-71975-y
