Thursday, May 12, 2016

[Paleontology • 2016] Agaresuchus fontisensis • New Spanish Late Cretaceous Eusuchian reveals the Synchronic and Sympatric Presence of Two Allodaposuchids


Agaresuchus fontisensis 
Narváez, Brochu, Escaso, Pérez-García & Ortega, 2016   DOI:  10.1016/j.cretres.2016.04.018

Highlights
• A new Late Cretaceous European basal eusuchian crocodyliform is described.
• Iberian species Allodaposuchus subjuniperus is reassigned to new genus Agaresuchus.
• Phylogenetic analysis suggests Allodaposuchidae as the sister group of Crocodylia.
• Synchronic and sympatric presence of two allodaposuchids in a fossil site is revealed.

Abstract
The recently described clade Allodaposuchidae includes European eusuchian crocodyliforms restricted to the Late Cretaceous (Campanian and Maastrichtian). A new allodaposuchid crocodyliform is here described based on two specimens from the upper Campanian–lower Maastrichtian fossil site of Lo Hueco (Cuenca, Spain). This new taxon, Agaresuchus fontisensis gen. et sp. nov., is described by two complete skulls and a lower jaw associated with one of them. This new species can be distinguished unambiguously from Lohuecosuchus megadontos, the other allodaposuchid known from the same fossil site. The presence of two allodaposuchid crocodyliforms in Lo Hueco allows the recognition of the synchronic and sympatric existence of two representatives of this clade for the first time. The new genus Agaresuchus, comprises a previously described Iberian allodaposuchid species, “Allodaposuchus” subjuniperus, as Agaresuchus subjuniperus, new combination.

Keywords: Basal Eusuchia; Allodaposuchidae; Agaresuchus gen. nov.; Agaresuchus fontisensis sp. nov.; Uppermost Cretaceous; Europe








Conclusions

Study of the eusuchian crocodyliforms from the Upper Cretaceous fossil site of Lo Hueco (Cuenca, Spain) confirms the existence of two different species: Lohuecosuchus megadontos Narváez et al., 2015 and Agaresuchus fontisensis described here. These two eusuchians allow a review of the phylogenetic position of several European Campanian–Maastrichtian specimens. As suggested by Narváez et al. (2015), the genus Allodaposuchus should be restricted to specimens from central and eastern Europe ( Nopcsa, 1928 and Delfino et al., 2008), while both in the Iberian Peninsula and in southern France, allodaposuchid specimens are identified as members of a clade. Thus, a vicariant distribution pattern, like that recognized for other European Late Cretaceous vertebrate clades ( Le Loeuff, 1991, Pereda-Suberbiola, 2009, Weishampel et al., 2010 and Csiki-Sava et al., 2015), is identified for this lineage of crocodiles.

In addition, the phylogenetic analysis reveals a more derived position for Allodaposuchidae than that proposed by Narváez et al. (2015). This clade is here supported as the sister group of Crocodylia. The lineage including Hylaeochampsidae is obtained as the most basal clade within Eusuchia, but an in-depth review of this group is necessary in order to clarify the phylogenetic position of Pietraroiasuchus, Pachycheilosuchus and Shamosuchus.

The study of Ag. fontisensis has allowed attribution of another species to Agaresuchus: Allodaposuchus subjuniperus ( Puértolas-Pascual et al., 2014).

On the other hand, the description of a new eusuchian member belonging to Allodaposuchidae in Lo Hueco allows recognition for the first time of the synchronic and sympatric existence of two representatives of this clade. Therefore, the allocation of fragmentary material found in a single locality or area to the same taxon must be considered with caution.


I. Narváez, C.A. Brochu, F. Escaso, A. Pérez-García and F. Ortega. 2016. New Spanish Late Cretaceous Eusuchian reveals the Synchronic and Sympatric Presence of Two Allodaposuchids. Cretaceous Research. 65; 112–125. DOI:  10.1016/j.cretres.2016.04.018

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