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Dryadissector, new varanoid lizard from Cretaceous to Texas, found in theropod tooth assemblage



Ben Creisler
bcreisler@gmail.com

A new online paper:

Steven L. Wick, Thomas M. Lehman & Alyson A. Brink (2014)
A theropod tooth assemblage from the lower Aguja Formation (early
Campanian) of West Texas, and the roles of small theropod and varanoid
lizard mesopredators in a tropical predator guild.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2014.11.018
http://www.sciencedirect.com/science/article/pii/S0031018214005835

Highlights

A new theropod tooth assemblage from the early Campanian of West Texas
is described

We conduct comparisons with similarly-aged North American paleofaunas

Small theropod species in North America are latitudinally-arrayed

A new varanoid lizard is described which occupied a similar ecological
niche as small theropods
Competition among paleomesopredators is analogous to a modern day
tropical predator guild


Abstract

A theropod tooth assemblage from the lower shale member of the Aguja
Formation in West Texas is part of a diverse microvertebrate fauna,
designated the Lowerverse local fauna, of early Campanian age (c. 80 –
82 Ma). The fauna includes as many as nine distinct theropod taxa
along with several indeterminate archosaurs and birds. Theropod tooth
types (indeterminate tyrannosaurids, cf. Saurornitholestes, cf.
Richardoestesia, cf. Paronychodon) are similar to those found in the
upper shale member of the Aguja, as well as in other Campanian
theropod assemblages from western North America. However, the most
abundant tooth morphotype is unique, and attributed to a new varanoid
lizard with remarkably theropod-like dentition, herein designated
Dryadissector shilleri (gen. et sp. nov.). The presence of many unique
theropod tooth morphotypes in the Lowerverse local fauna suggests that
there remains significant undiscovered diversity among small theropods
in southern latitude faunas, and accords with recognition of distinct
latitudinal biomes during Campanian time in western North America. Due
to their similar dentition, small theropods, along with varanoid
lizards, may have served similar ecological roles as competitive
mesopredators in the Campanian tropical predator guild.