A new crocodylomorph of “mesosuchian” grade from the Upper Cretaceous upper Milk River Formation, southern Alberta

Morphology of the Late Cretaceous Crocodylomorph Shamosuchus djadochtaensis and a Discussion of Neosuchian Phylogeny as Related to the Origin of Eusuchia

“…Susisuchus anatoceps and Isisfordia duncani are depicted as successively more closely related to Hylaeochampsa vectiana and eusuchians than Bernissartia fagesii, as interpreted by Salisbury et al (2006). Glichristosuchus palatinus is similarly depicted as closer to eusuchians than Bernissartia fagesii, in agreement with the hypothesis presented by Wu and Brinkman (1993) and Allodaposuchus precedens is retrieved as closer to crocodylians than Hylaeochampsa vectiana as in Buscalioni et al (2001). This consistency of results was not expected given that our dataset differs in terms of taxon and character sampling with respect to the various datasets used in previous studies of the relationships of these five taxa.…”

“…For instance, the position of Isisfordia duncani and Susisuchus anatoceps relative to the Asian clade or Glichristosuchus palatinus (see fig. 39) had not been tested in previous studies (e.g., Wu and Brinkman, 1993;Salisbury et al, 2006).…”

“…As we have not examined the specimens, these scorings have been taken from the original publication with the same coding strategy described above for Isisfordia duncani and Susisuchus anatoceps (and therefore the results should be taken with similar caveats; see appendix 4 for these scorings). Another relevant neosuchian from North America is Glichristosuchus palatinus (Wu and Brinkman, 1993) from the Milk River Formation (Santonian-Campanian) of Canada. Although this taxon is known from an incomplete small specimen (partial skull and cervical vertebra) it has been interpreted as an advanced neosuchian, purportedly more closely related to Eusuchia than Bernissartia fagesii (Wu and Brinkman, 1993).…”

“…Another relevant neosuchian from North America is Glichristosuchus palatinus (Wu and Brinkman, 1993) from the Milk River Formation (Santonian-Campanian) of Canada. Although this taxon is known from an incomplete small specimen (partial skull and cervical vertebra) it has been interpreted as an advanced neosuchian, purportedly more closely related to Eusuchia than Bernissartia fagesii (Wu and Brinkman, 1993). This interpretation is based on the presence of a unique combination of derived and plesiomorphic characters.…”

“…Therefore the proposed phylogenetic position of this taxon (Wu and Brinkman, 1993) needs to be tested within a comprehensive phylogenetic context. Although the available information on this taxon is limited because of the incompleteness of the type specimen (Wu and Brinkman, 1993) and we have not examined the specimens, a preliminary scoring of this taxon in our dataset was performed following the same coding strategy described above (see appendix 4). The exploratory analysis on the position of Glichristosuchus palatinus retrieves this taxon in multiple equally parsimonious positions ( fig.…”