Abstract
BackgroundThe neosuchian crocodyliform genus Hulkepholis constitutes the longirostral lineage of the European Goniopholididae. It comprises two species ranging from the Valanginian of southern England to the lower Albian of the northern Teruel (Spain). A new species of Hulkepholis is described based on a partially complete skull from the lower Barremian Camarillas Formation. We investigate its phylogenetic position and the palatal patterns among members of Goniopholididae and the closely related Thalattosuchia and Tethysuchia.MethodsPhylogenetic relationships were investigated with two matrices using a previously published dataset as the basis: the first differed only by the addition of the new species, the second had newly discovered states for 11 characters, the new species plus several additional specimens of Hulkepholis and Anteophthalmosuchus. Both matrices were processed using TNT v. 1.1, in a heuristic analysis of maximum parsimony, with tree bisection and reconnection 1,000 random addition replicates and saving the 10 most parsimonious trees per replicate, and up to 10 suboptimal trees to calculate Bremer supports. The skull geometry of nine species from Thalattosuchia, Tethysuchia and Goniopholididae was explored to test shape variation between the rostral and postrostral modules, and to visualize the differences on the secondary palate. A set of 18 landmarks was used to delimit significant anatomical features, and the skulls were isotropically scaled using Adobe Illustrator, with the longest skull (Sarcosuchus imperator) as the baseline for comparison.ResultsThe European lineages of goniopholidids are two clades (Nannosuchus + Goniopholis) plus (Hulkepholis + Anteophthalmosuchus). The new species, Hulkepholis rori sp. nov, shares with the latter clade the following apormorphies: a long anterolateral postorbital process, postorbital process almost reaching the anterior jugal ramus, and basioccipital tubera with lateral edges turned posteriorly. Anteophthalmosuchus was found to be monophyletic, and Hulkepholis paraphyletic due to the poor preservation of H. willetti. Hulkepholis rori is distinguished by having vascular fossae and a mid-protuberance on the ventral surface of the basioccipital, and wide internal fossae in the quadrate. Among Goniopholididae differences on the secondary palate are the presence of a palatal cleft, the narrowness of the secondary choana, and a wide foramen of the median pharyngeal tube.ConclusionsThe new species is the earliest Hulkepholis from the Iberian Peninsula. New characters have been recognized in the organization of the palate and in the occipital region raising unexpected questions on the evolution of Goniopholididae. The set of palatal characters is discussed as part of a singular palatogenesis in Goniopholididae. The protruding occipital areas suggest that the longirostral Hulkepholis would have had an aquatic lifestyle with particular neck and skull movements.
Highlights
Goniopholididae is a well-known extinct family of neosuchian crocodyliforms
The neosuchian crocodyliform genus Hulkepholis constitutes the longirostral lineage of the European Goniopholididae
Code as such, conditions observed in the hyperadult, such as the presence of a well-defined postnarial fossa with wide pits and a deep sulcus, the greater size of the supratemporal fossa relative to the orbits, the relative increase of the rostral length, the orbital lateral displacement, and the greater ornamentation of the squamosal at the posterolateral lobes
Summary
Goniopholididae is a well-known extinct family of neosuchian crocodyliforms. They have a Jurassic origin, with Calsoyasuchus valliceps (Tykoski et al, 2002) from North America, probably one of its earliest known members (Sinemurian-Pliensbachian) (Wilberg, Turner & Brochu, 2019). The family possesses a set of primitive features (e.g., palatines participating in the choana, amphicoelous vertebrae, two rows of paravertebral osteoderms) together with several characteristic traits, such as an extremely flattened rostrum, maxillary depressions, two parasagittal palatal fossae, and an open cranioquadrate passage (Steel, 1973; Buffetaut, 1982; De Andrade et al, 2011; Adams, 2013) Despite their abundant and diverse fossil record, the phenotypic variability and functionality of goniopholidid features are not yet fully understood, which is corroborated by the incongruence between taxonomy and phylogeny (De Andrade et al, 2011; Allen, 2012; Pritchard et al, 2013; Adams, 2013; Puértolas-Pascual, Canudo & Sender, 2015; Martin, Delfino & Smith, 2016; Ristevski et al, 2018).
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