Friday, February 12, 2010

Alioramus Dinosaur


His only known representative, Alioramus remotus was smaller than its giant
relatives as Tyrannosaurus rex and Tarbosaurus, although the only known specimen
is a juvenile, the estimate of adult size is difficult.


Its name means Reptile another branch


Characteristic


* Time: (-144 M.A. at -65 M.A.)

*
Size: 6 m long, 3.4 m high, 680 kg

*
Habitat: Asia

*
Diet: carnivorous


Etymology


This dinosaur was named and was described by Russian paleontologist Sergei
Kurzanov in 1976.

At the beginning of the restoration, the ridges and the low profile of the skull
of this dinosaur have appeared so different from other tyrannosaurids he was
named dAlioramus of Latin aliases (alternate) and ramus (branch).

This refers to the belief Kurzanov quAlioramus belonged to a new branch of
evolution different from that of tyrannosaurids.

Similarly, the name of the species (A. remotus) also refers to its
characteristic remotus in Latin means "removed".





As its name suggests, Alioramus was not far from being excluded from
tyrannosauroides.

However, several recent reviews have placed in the family Tyrannosauridae.


A cladistic analysis of 2004 square Alioramus, or just outside Tyrannosauridae,
or inside, in the subfamily Tyrannosaurinae.





Other studies support the last hypothesis, putting Alioramus as taxon brother
Tarbosaurus in Tyrannosaurinae.


Anatomy


Alioramus had a head longer and smaller and more numerous teeth than other
tyrannosaurs.

It was small and slender and had six small horns on his long snout, one on each
side and four in the middle in one row.

Too small to defend themselves, these horns could have been of secondary sexual
characteristics, identifying males and females


Inventory of fossil found


Alioramus is not well known, with only a partial skull and 3 metatarsal bones
available for study.

The skull is about 45 cm long and low profile, but not as much as skull restored
in the original description, with six distinctive bony ridges aligned in rows
where the nasal bones are found on the top of the snout.





Many of nasal tyrannosaurids irregular, but no none peak as developed as that of
Alioramus although Appalachiosaurus recently described to overtake.





Alioramus is also characterized by a large number of teeth of upper and lower
jaws.

One specimen exhibits 16 teeth in the maxilla (the upper jaw bone) and 18 in the
tooth (the bones of the lower jaw), more than any other known tyrannosaurids.


References


* Kurzanov, SM (1976).

[A new Late Cretaceous carnosaur from Nogon-tsav, Mongolia.] Journal of the
Soviet-Mongolian Paleontological Expeditions 3:93-104.

* Holtz, T.R. (2004).
Tyrannosauroidea.
In: Weishampel,
DA, Dodson, P., and Osmólska, H.
(Eds.).
The Dinosauria (2nd Edition).

University of California Press: Berkeley, 111-136.

ISBN 0-520- 24209-2

* Currie, P.J.,
Hurum J.H., and Sabath, K. 2003.
Skull
structure and evolution in tyrannosaurids phylogeny.

Acta Palaeontologica Polonica 48 (2) :227-234.

* Xu X., Norell,
M.A., Kuang X., Wang. X., Zhao Q.,
and Jia C. (2004).

Basal tyrannosauroids from China and evidence for protofeathers in
tyrannosauroids. Nature 431:680-684.

* Currie, P.J. (2003).

Tyrannosaurids Cranial anatomy of dinosaurs from the Late Cretaceous of Alberta,
Canada. Acta
Palaeontologica Polonica 48 (2) :191-226.

*
Carr, TD, Williamson, TE, and Schwimmer, DR (2005).

A new genus and species of tyrannosauroid from the Late Cretaceous (middle
Campanian) Demopolis Formation of Alabama.
Journal of
Vertebrate Paleontology 25 (1) :119-143.