Alcovasaurus
Name:
Alcovasaurus
(Alcova lizard).
Phonetic: Al-co-vah-sor-us.
Named By: Peter M. Galton & Kenneth
Carpenter - 2016.
Synonyms: Stegosaurus longispinus.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Thyreophora, Stegosauria, Stegosauridae.
Species: A. longispinus
(type).
Diet: Herbivore.
Size: Roughly estimated at about 5.7 meters long.
Known locations: USA, Wyoming - Morrison
Formation.
Time period: Late Jurassic.
Fossil representation: Partial post cranial skeleton
including vertebrae, ribs, ischia, partial pubis, right femur,
and four tail spines.
In
1914 the palaeontologist Charles Whitney Gilmore described a new
species of Stegosaurus
which he named S. longispinus. The name was
chosen as a reflection of the unusually large tail spines that were
much longer than those seen in other Stegosaurus
fossils. For many
years however the validity of S. longispinus was
called into question
with the long spines possibly representing a case of sexual dimorphism
and there for display. However others such Olshevsky and Ford in
1993 speculated that Stegosaurus longispinus may
in fact be an
American species of Kentrosaurus
which is known from Africa. Studies
were hampered however when the type specimen was damaged by water from
a burst pipe at the University of Wyoming and was thought lost,
though fossils are now known again.
In
2014 a freelance palaeontologist named Roman Ulansky self-published
an article online of his own opinion that Stegosaurus
longispinus was
not a valid species of Stegosaurus, and agreeing
with the previous
interpretation that S. longispinus was more
similar to Kentrosaurus,
created a new genus name for S. longispinus.
This new genus name
was called Natronasaurus, after Natrona County which is the generic
location where the type fossils of S. longispinus
had been found.
Problems soon arose however as even though the new name gained quick
popularity on the internet, it was never officially valid. The
problem was that the paper describing Natronasaurus was self-published
without peer review association, and on top of this the paper didn’t
have a valid ISSN number. Therefore, while the paper made a clear
and valid point about S. longispinus, it could
never be accepted as
scientifically valid without those two things.
In
2016 yet another new name for S. longispinus
was proposed, this
time by veteran palaeontologists Peter M. Galton and Kenneth
Carpenter, and this time in a peer reviewed journal. Their new name
for S. longispinus was Alcovasaurus
which means ‘Alcova lizard’,
after the Alcova Quarry in Natrona County in Wyoming which is the
specific location in Natrona County where fossils of Alcovasaurus
were
found. Stegosaurus is still a valid genus in its
own right, but the
former species S. longispinus is now a synonym to
Alcovasaurus,
with the species name used to establish the new type species,
Alcovasaurus longispinus. Because Natronasaurus
was never officially
documented it is now seen as an invalid name, and because it is
invalid, it cannot even exist as a synonym to Alcovasaurus.
With
an estimated length of about 5.7 meters for the holotype
individual, Alcovasaurus would have been a medium
sized stegosaurid
dinosaur, and one speculated to be more like Kentrosaurus
than
Stegosaurus. However, at the time of writing
only four tail spines
are known, and the full pattern of spines and possible plates along
the back is still unknown. For this reason reconstructions are
usually based upon Kentrosaurus which is known to
have small plates on
the anterior (front) half of the body, and long spines on the
posterior (rear) half of the body. Like all stegosaurid
dinosaurs, Alcovasaurus would have been a browser
of low growing
vegetation while ornithopod and sauropod
dinosaurs would have browsed
the medium and high levels.
Possible
predatory threats to Alcovasaurus include Allosaurus,
Torvosaurus,
Fosterovenator
and possibly also Ceratosaurus.
Further reading
- Osteology of the armoured Dinosauria in the United States National
Museum, with special reference to the genus Stegosaurus.
- United
States National Museum Bulletin 89: 1–143. - Charles Whitney
Gilmore - 1914.
- The origin and evolution of the stegosaurs. - Gakken Mook,
Dinosaur Frontline, v. 4, p. 65-103. - G. Olshevsky
& T. L. Ford - 1993.
- Evolution of the stegosaurs (Dinosauria; Ornithischia). -
Dinologia, 35 pp. [in Russian]. - Roman E. Ulansky -
2014.
- The plated dinosaur Stegosaurus longispinus
Gilmore, 1914
(Dinosauria: Ornithischia; Upper Jurassic, western USA),
type species of Alcovasaurus n. gen. - Neues
Jahrbuch f�r
Geologie und Pal�ontologie - Abhandlungen 279(2): 185-208.
- Peter M. Galton & Kenneth Carpenter - 2016
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