Alvarezsaurus
Name:
Alvarezsaurus
(Alvarez’s lizard).
Phonetic: Al-vah-rez-sore-us.
Named By: Jose F. Bonaparte - 1991.
Synonyms: Achillesaurus?
Classification: Chordata, Reptilia,
Dinosauria, Saurischia, Theropoda, Alvarezsauroidea,
Alvarezsauridae.
Species: A. calvoi (type).
Diet: Insectivore?
Size: Estimated about 1.2 meters long.
Known locations: Argentina - Bajo de la Carpa
Formation.
Time period: Santonian of the Cretaceous.
Fossil representation: Partial remains.
Alvarezsaurus
was the first of a group of dinosaurs that were first discovered late
into the twentieth century. Since it was the first, Alvarezsaurus
was used to name this new group which became known as the
alvarezsaurs.
At the time of writing there are now several genera of
alvarezsaurs known to us, but in a twist the type genus,
Alvarezsaurus, has remained one of the most
incomplete and least
understood. This is not the first time that such a thing has happened
though, the ankylosaurs,
the armoured herbivorous dinosaurs with
clubbed tails are named after one of the most famous dinosaurs of all
time, Ankylosaurus,
yet Ankylosaurus is one of
the most incomplete
of these. Alvarezsaurus was named in honour of
the historian Don
Gregorio Alvarez, and not after Luis Alvarez a famous physicist and
‘amateur’ palaeontologist who was among the first to suggest that a
comet or meteor was responsible for causing the KT extinction and
wiping out the dinosaurs.
Alvarezsaurus
has been estimated at about two meters long, something which makes it
large for its kind. Alvarezsaurus also seems to
have been quite
primitive in form when compared to other genera. Like its relatives
Alvarezsaurus is noted for having an enlarged finger
with a large
claw. The popular consensus is that this claw was used to jab holes
into the sides of termite mounds so that an individual Alvarezsaurus
could pick off individual termites. Modelling studies however have so
far not shown a lot of support for this theory, though it has not
been discounted completely. It may be that the true function of the
finger still remains unknown to us at the time of writing.
Another
alvarezsaurid known from the same formation as Alvaresaurus
is the
genus Achillesaurus.
Although still often treated as a distinct
genus, at the time of writing at least one study (Makovicky et al,
2012) has considered that this genus might be a synonym to
Alvarezsaurus.
Further reading
- Los vertebrados f�siles de la Formaci�n Rio Colorado, de la
Ciudad de Neuqu�n y Cercan�as, Cret�cico Superior, Argentina [The
vertebrate fossils of the Rio Colorado Formation, from the city of
Neuqu�n and surrounding areas, Upper Cretaceous, Argentina]. -
Revista del Museo Argentino de Ciencias Naturales "Bernardino
Rivadavia" e Instituto Nacional de Investigaci�n de las Ciencias
Naturales: Paleontolog�a 4(3):17-123 - Jose F. Bonaparte
- 1991.
- A New Coelurosaurian Theropod from the La Buitrera Fossil Locality
of R�o Negro, Argentina. - Fieldiana Life and Earth Sciences
5: 90. - P. J. Makovicky, S. N. Apestegu�a &
F. A. Gianechini - 2012.
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