Magnosaurus
Name:
Magnosaurus
(Large lizard).
Phonetic: Mag-noe-sore-us.
Named By: Friedrich von Huene - 1932.
Synonyms: Megalosaurus nethercombensis,
Megalosaurus lydekkeri. Eustreptospondylus
and Sarcosaurus are also sometimes considered to be
synonyms.
Classification: Chordata, Reptilia, Dinosauria,
Theropoda, Megalosauridae.
Species: M. nethercombensis
(type),
M. lydekkeri, M. woodwardi.
Diet: Carnivore.
Size: Roughly estimated to be around 4 meters
long, possibly slightly bigger.
Known locations: England, Dorset - Inferior
Oolite.
Time period: Mid Jurassic.
Fossil representation: Partial post cranial remains
and lower jaw, possibly of a juvenile.
Palaeontology
as we know it today has its foundation in nineteenth century Europe and
dinosaurs first began to be named and classified in England in the
first half of that century. As the first named dinosaur,
Megalosaurus
was the first dinosaur genus to have a taxonomic
placement amongst other recognised animals, however this also led to
it being becoming what is termed a ‘wastebasket taxon’ where any
remotely similar remains are attributed to the genus. Later study of
fossils attributed to Megalosaurus has revealed
that some of the
remains represent different animals upon a genus rather than a species
level and it was such a discovery that led to the naming of Magnosaurus.
In
1923 Friedrich von Huene named a new species of Megalosaurus
from
very partial remains from the Inferior Oolite of England as M.
nethercombensis. In 1926 von Huene created the species
M.
lydekkeri from the description of some teeth. In 1932
however
von Huene created a new genus for these two species as Magnosaurus
with
the type species being Magnosaurus nethercombensis
with Magnosaurus
lydekkeri still being based upon a tooth description.
It
is with the 1932 creation of Magnosaurus that
things start to get
complicated since von Huene also created a third species of M.
woodwardi based upon a tibia (lower leg bone). At this
time von
Huene also classified this tibia as belonging to a new species of
Sarcosaurus
called S. andrewsi, but also renamed the Sarcosaurus
type species as Magnosaurus woodi. In 1956
von Huene swayed in
favour of Sarcosaurus having priority although in
1974 S.
andrewsi was reclassified as a species of Megalosaurus,
although
many other researchers continue to treat it as a nomen dubia. Further
classification arose in 2003 when a paper by Rauhut proposed that
Magnosaurus and Eustreptospondylus
were the same genus of dinosaur
because they both share an expanded tip to their lower jaw as well as
an enlarged front tooth. Such a change would mean that
Eustreptospondylus would only exist as a junior
synonym to Magnosaurus.
Today
both M. lydekkeri and M. woodwardi
are both considered to be
dubious species of Magnosaurus due to the overall
lack of identifiable
characteristics. Sarcosaurus and Eustreptospondylus
are also
sometimes written as the additional species of M woodi
and M.
oxoniensis. Universally however only the type species of
Magnosaurus, M. nethercombensis
is recognised as being valid.
As
a dinosaur Magnosaurus inhabited north-western
Europe at a time when
much of the continent was submerged. This resulted in a series of
reduced land masses that resembled a continuous island chain across
what is now a single continent. The type specimen fossils come from
an individual that is estimated to have been around four meters long,
though if these remains are of a juvenile as has been suggested,
adults would have certainly been bigger. Magnosaurus
inhabited the
same habitat as the theropods Dubreuillosaurus
and Megalosaurus, as well
as the sauropod
dinosaur Cetiosaurus.
Further reading
- Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und
Geschichte [The fossil reptile order Saurischia, their development and
history]. - Monographien zur Geologie und Palaeontologie, serie 1
4(1-2):1-361. - F. von Huene - 1932.
- The osteology of Magnosaurus nethercombensis
(Dinosauria, Theropoda)
from the Bajocian (Middle Jurassic) of the United Kingdom and a
re-examination of the oldest records of tetanurans. - Journal of
Systematic Palaeontology, 8(1): 131-146. - Roger B. J. Benson - 2010.
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