A new ophthalmosaurid ichthyosaur from the Early Cretaceous of Colombia

Abstract

Cretaceous ichthyosaurs were relatively diverse in temperate latitudes, but few species have been described from the palaeotropics. Here, we describe a new ophthalmosaurid ichthyosaur, Muiscasaurus catheti gen. et sp. nov., from the Barremian–Aptian aged Paja Formation of Colombia. This species is known only from a partial skull and differs from all other ichthyosaurs in the unusual configuration of the external narial opening, slender rostrum, narrow postorbital region, and gracile dentition. It is the second ichthyosaur described from the Paja Formation, suggesting moderate taxonomic and ecological ichthyosaur diversity in the region during the Early Cretaceous.

Revision ofUndorosaurus, a mysterious Late Jurassic ichthyosaur of the Boreal Realm

“…Clade 'A' has relatively high Bootstrap (58) and Jackknife (67), thus being the most well supported clade in our analysis. Similar clades were also recovered by Maxwell et al (2016) and Paparella et al (2017). However, contra their results, our analysis do not support close relations of this clade with 'Cryopterygius kristiansenae' (i.e.…”

“…Keilhauia nui (Delsett et al 2017). A similar explanation could be proposed for the recovery of Undorosaurus close to the base of Ophthalmosauridae in a number of previous analyses (Roberts et al Maxwell et al 2016;Delsett et al 2017;Paparella et al 2017). It is worth mentioning that similar phylogenetic position of Nannopterygius as a sister group to other Ophthalmosauridae was recently hypothesised by Maisch (2015), however, without a formal analysis.…”

“…However, the presence of the squamosal in certain ophthalmosaurids should be further considered with great caution, as this element is very thin and poorly attached to the rest of postorbital bar. In this regard, coding the squamosal as absent could give a misleading phylogenetic signal, as in the case with its 'absence' in Cryopterygius kristiansenae and Palvennia hoybergeti indicated by Druckenmiller et al (2012) and further considered in all recent phylogenies (Roberts et al Maxwell et al 2016;Ji et al 2016;Fischer et al 2016;Delsett et al 2017;Moon 2017;Paparella et al 2017).…”

Two new species of Ichthyosaurus from the lowermost Jurassic (Hettangian) of Somerset, England

“…; Maxwell et al . ) was not included in the outgroup because only forefin and scapula characters could be coded (however, see below).…”

Restos apendiculares de un ictiosaurio oftalmosáurido del Barremiano inferior de Villa de Leiva, Colombia

“…En el trabajo de Fischer et al (2012) (Fischer et al, 2013a;Fischer et al, 2014a;Fischer et al, 2014b;Roberts et al, 2014;Druckenmiller y Maxwell, 2014;Zverkov et al, 2015). Sin embargo, en algunos análisis filogenéticos no se reconocen subgrupos dentro de Ophthalmosauridae (Fernández y Talevi, 2014;Maxwell et al, 2015;Ji et al, 2016). En el trabajo de Ji et al (2016) se ofrecen las más recientes diagnosis de los géneros de la familia Ophthalmosauridae.…”