Elosuchus broinae, Meunier & Larsson, 2017

ELOSUCHUS BROINAE SP. NOV

ZooBank Life Science Identifier (LSID) for new species.

urn:lsid:zoobank.org:act: [41275ED6-D295-430A-B838- FB8353A9DB39]

Holotype. SAM 129 ( Fig. 16 View Figure 16 ).

Etymology. In honour of the contributions of France de Lapparent de Broin to north African vertebrate palaeontology.

Revised distribution. Algeria (Gara Samani) ( Fig. 1B View Figure 1 ).

Age . Cretaceous (Late Albian). Of note is that even though the geological deposits of this specimen are more terrestrial and underly the Cenomanian transgression limestone that is probably continuous with the Moroccan Akrabou Formation, the age of these continental rocks is slightly older, dated to the Late Albian, rather than the Cenomanian Kem Kem beds.

Diagnosis. Same as for the genus but with the addition of: distinct maxilla – jugal groove; postorbital bar orientated anteroventrally; postorbital bar with a sigmoidal margin at anteroventral corner of infratemporal fenestra; postorbital bar columnar with a subcircular cross-section; postorbital bar not flaring anteriorly ventrally; squamosal notched over auditory meatus in lateral view; broad and sculpted anterior and posterior supratemporal bars; hypertrophied muscle scar on lateral surface of posteroventral ramus of squamosal; incised groove at posterior end of posterior quadrate – squamosal contact.

DESCRIPTION

In SAM 129, a shallow groove is present across the jugal – maxilla external suture ( Fig. 17A View Figure 17 ). This depression extends from an anteroventrally directed foramen on the jugal, arches gently anteriorly across the jugal – maxilla contact, and continues horizontally onto the maxilla before gradually terminating over the second-last alveolus. A similar morphology is also present in Sarcosuchus imperator but in this taxon the anterior extent of the groove terminates in a slitlike foramen at the surface of the maxilla (GDF 380, GDF 662). However, no other specimen of Elosuchus that we examined has this morphology. Either this groove is polymorphic within the genus or SAM 129 represents a unique species sister to E. cherifiensis .

Martin & Buffetaut (2012) reviewed the presence of the maxillary depression within Pholidosauridae . This depression was first identified in Goniopholis ( Buffetaut, 1982) . It is a deep, elongate fossa on the posterolateral surface of the maxilla that excavates around the posterior alveolae. Within the fossa, three smaller fossae are lined along the long axis and are pierced in their centres by a neurovascular foramen. Other goniopholidids, such as Eutretauranosuchus delfsi Mook, 1967 ( Pritchard et al., 2013), have a similar, deep, ovate maxillary depression. Martin & Buffetaut (2012) equated this depression with the jugal – maxillary groove present in Sarcosuchus and SAM 129 ( Martin & Buffetaut, 2012: figs 1D, 4A, B). Although the neurovascular component of the jugal – maxilla groove in Sarcosuchus and SAM 129 and maxillary depression of goniopholidids may have been homologous, the morphology is radically different. We do not support equating the jugal – maxilla groove of Sarcosuchus and SAM 129 with the goniopholidid maxillary depression because: the groove begins with a foramen on the jugal whereas the depression has no extension onto nor receives a groove or foramen from the jugal; the depression is deep and pierced by multiple neurovascular foramina whereas the groove in SAM 129 has no maxillary foramen and that of Sarcosuchus has a single, slitlike foramen. More work is needed on this morphology to clarify its evolutionary variation. Other pholidosaurids, such as Pholidosaurus sp. (CHE03.100), have a limited maxillary depression over the maxilla but lack a deep fossa or distinct foramina. Terminonaris robusta has a ‘groove-like depression’ that extends over the maxillary alveolae, but no trace of it extending from a depression nor from the jugal ( Wu et al., 2001: 496).

The dorsal skull table is heavily sculpted. Both the anterior and the posterior supratemporal bars are broad and fully sculpted. Laterally, the ventral departure from this line is on the bar at the anteroventral corner of the infratemporal fenestra, where the jugal has a distinct tab extending into the fenestra. The columnar postorbital bar is also relatively straight on its lateral surface, making the passage between the orbit and infratemporal fenestra relatively flat, unlike the circular passage of E. cherifiensis .

Posterior to the external auditory meatus is a hypertrophied muscle scar on the lateral surface of the posteroventral ramus of the squamosal. This scar is only present as a low bump in E. cherifiensis , but is striate and raised in E. broinae . This muscle scar is further developed by a deeply incised groove at the posterior end of the posterior quadrate – squamosal contact. This groove is normally rather shallow in crocodyliformes, including E. cherifiensis .