Garudimimus in the Canadian Journal of Earth Sciences

[Darryl Jones <dinoguy@sympatico.ca>]

I haven't seen this posted yet (I apologise if it has been):

Kobayashi, Yoshitsugu and Barsbold, Rinchen (2005).  Reexamination of a
primitive ornithomimosaur, Garudimimus brevipes Barsbold, 1981 (Dinosauria:
Theropoda), from the Late Cretaceous of Mongolia. Canadian Journal of Earth
Sciences, 42: 1501-1521.

Abstract: The holotype of Garudimimus brevipes, discovered from the Upper
Cretaceous sediments of Mongolia and named by Barsbold in 1981, is redescribed
in detail in this paper. Reexamination of the holotype reveals a great deal of
anatomical information, which allows us to revise the original diagnosis of this
taxon and make comparisons with other ornithomimosaur taxa to understand the
evolution of ornithomimosaurs. This paper suggests that characters used to
differentiate this taxon in the original paper (short ilia, short metatarsals,
exposure of the proximal end of metatarsal III, presence of pedal digit I, and
absence of pleurocoels) are not apomorphies but represent the primitive
conditions in ornithomimosaurs and are symplesiomorphies. Revised diagnoses are
assigned for G. brevipes (posteriorly positioned jaw articulation, fossae at
base of dorsal process of supraoccipital, paired depressions on neural spines of
proximal caudal vertebra, and deep groove on lateral surface of pedal phalanges
III-1 and III-2). Metatarsals of Garudimimus display a non-arctometatarsalian
condition as in an Early Cretaceous form, Harpymimus, but the constriction of
metatarsal III in Garudimimus is intermediate between Harpymimus and the
arctometatarsalian condition in Gallimimus and other derived ornithomimosaurs
(ornithomimids). Garudimimus is the only non-ornithomimid ornithomimosaur with
edentulous jaws, which were probably covered by rhamphothecae. The loss of teeth
with evolution of rhamphothecae and development of a cutting edge in the dentary
of Garudimimus suggest the acquisition of feeding habits that included plucking
food
at the anterior portion of the jaw and cutting at the middle portion, similar to
ornithomimids.

Darryl Jones  <dinoguy@sympatico.ca>


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