Basal sauropodomorphs (Dinosauria: Saurischia) from the Lower Jurassic of India: their anatomy and relationships

Abstract

The Upper Dharmaram Formation (Lower Jurassic, Sinemurian) of India has yielded three sauropodomorph dinosaurs, two new taxa and an indeterminate one.Lamplughsaura dharmaramensisn. gen. and sp., represented by several partial skeletons, is a heavily built quadrupedal form (body length ~10 m). Autapomorphies include teeth with strongly emarginated distal edge; caudal cervical neural spines bearing a vertically oriented ligamentous furrow on cranial and caudal surfaces and a transversely expanded spine table; caudal neural spines bearing a craniodorsally directed spur (proximal caudal vertebrae) or a large process (midcaudal vertebrae); caudal neural spines shorter than transverse processes so former lost first in passing along tail; and a plesiomorphy that is the nontrenchant form of manual ungual I. The Indian dinosaurs were coded for two recent datamatrices for basal sauropodomorphs. The results of this preliminary analysis indicate thatLamplughsaurais either a basal Sauropoda or, less likely, based on Templeton's test, a stem sauropodomorph. The second large form, represented by the proximal half of a femur, is a sauropodomorph that is more derived thanSaturnalia(Brazil) andThecodontosaurus(Great Britain) from the Upper Triassic. This is also true for the smaller (body length ~4 m as adult)Pradhania gracilisn. gen. and sp. which lies outside of the Sauropoda + Plateosauria clade, so it is definitely a stem sauropodomorph.Pradhaniais known from fragmentary material; an autapomorphy is the very prominent medial longitudinal ridge on the maxilla.