A possible new specimen of the Late Cretaceous Mongolian sauropod Nemegtosaurus and sauropod diversity in the Nemegt Formation

Alexander Averianov,Alexey Lopatin

doi:10.4202/app.00596.2019

Abstract

A possible new specimen of the Late Cretaceous Mongolian sauropod Nemegtosaurus and sauropod diversity in the Nemegt Formation

Highlights

There are two sauropod taxa known from the Upper Cretaceous (Maastrichtian) Nemegt Formation of Gobi Desert, Mongolia: Nemegtosaurus from the Nemegt locality and Opisthocoelicaudia from the Altan Uul IV locality
Five articulated sauropod dorsal vertebrae (PIN 3837/P821, dorsals 6–10) were found in 1949 by the Mongolian Expedition of the Academy of Sciences of the USSR at the Nemegt locality. This specimen is similar to Opisthocoelicaudia in having a strong ventral ridge on dorsal centra, a low neural arch which is anteroposteriorly narrowest at the junction with the centrum and widens dorsally, and lack of hyposphene–hypantrum articulations
PIN 3837/P821 differs from Opisthocoelicaudia by having the less dorsoventrally flattened dorsal centra, a shallow ventral concavity of dorsal centra in lateral view, a vertical posterior centrodiapophyseal lamina in dorsals 8 and 9, a postzygodiapophyseal lamina that roofs the centrodiapophyseal fossa, and strongly developed accessory laminae within the parapophyseal centrodiapophyseal fossa

Summary

Introduction

There are two sauropod taxa known from the Upper Cretaceous (Maastrichtian) Nemegt Formation of Gobi Desert, Mongolia: Nemegtosaurus from the Nemegt locality and Opisthocoelicaudia from the Altan Uul IV locality. Both taxa are represented by not overlapping elements (skull and partial postcranial skeleton respectively), which arises question on their possible synonymy.

Results

Conclusion