Fendusaurus

Fendusaurus was an extinct genus of sauropodomorph dinosaur that lived during the earliest Jurassic of eastern North America. The type and only species is F. eldoni, and it was named and described in 2007 by Timothy J. Fedak. One paleontologist, Adam Douglas Marsh, stated that the original naming of Fendusaurus was possibly invalid for describing a new taxon. If Fendusaurus can be considered valid, five specimens, FGM998GF13-II, FGM998GF13-I, FGM998GF13-III, FGM998GF69, FGM998GF9, and FGM998GF18 can be referred to it. They can be referred to different individuals based on the femora and coracoidal count and shape. The specimens are all from the McCoy Brook Formation in Wasson Bluff, and share most of the same characteristics. They can be distinguished from cf. Ammosaurus by the ilium and sacral vertebrae morphology. Distinguishing features of Fendusaurus among massospondylids present, but are considered possibly invalid by Marsh. The morphological variation of the specimens were stated to be intra-specific variation, but some differences might prove there to be more than one taxon of sauropodomorph present in the formation.

Discovery and naming
Fendusaurus is known from five specimens of skeletal elements.[1] The specimens include a holotype, FGM998GF13-II,[2] that includes a skull, and cannot be assigned to cf. Ammosaurus.[1] Other specimens are also assigned to Fendusaurus, FGM998GF13-I, FGM998GF13-III, FGM998GF69, FGM998GF9, and FGM998GF18, all found by a crew from the Princeton University.[2] All the specimens include femora and coracoids, and although they each share slightly different features, the differences are credited to intra-specific variation. The femora and coracoids also help identify different individuals, and Timothy J. Fedak, the described of the specimens, found that each block represented about one individual.[1]

Adam Douglas Marsh published a short section in an article on Fendusaurus. He stated that the generic and specific names were not published, and found that Fendusaurus could be an invalid taxonomic name.[2] Fendusaurus eldoni was named and described by Fedak in 2007, after material originally assigned to Anchisaurus of Ammosaurus.

Description
The specimens of Fendusaurus include mostly crushed vertebrae, along with appendicular elements.[2] They are distinguishable from Ammosaurus by the morphology of both the ilium and sacral vertebrae. However, in some specimens, the morphology of the femora and coracoids are quite different, which led Fedak to speculate that more than one species may have been present.

Distinguishing characteristics
Fendusaurus, according to Fedak, can be distinguished from all closely related sauropodomorphs by the extreme elongation of the cervical vertebrae; a four vertebrae sacrum that includes a dorsosacral and caudosacral; the elongate postacetabular process of the ilium; and an expanded anterior distal process of the tibia.[1] Marsh found that the features are possibly present, but that Fendusaurus requires a reassessment to prove that it can be distinguished from other genera.