Maraapunisaurus
Name:
Maraapunisaurus
(huge lizard).
Phonetic: Ma-rah-pu-ne-sore-us.
Named By: Kenneth Carpenter- 2018
Synonyms: Amphicoelias fragillimus.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropoda, Rebbachisauridae.
Species: M. fragillimus
(type).
Diet: Herbivore.
Size: Highly speculative given that the genus is
based upon partial remains which have now become lost. Older
estimates from the time when Maraapunisaurus
fossils were attributed to
the Amphicoelias genus and reconstructed as a
diplodocid suggested
anywhere between 40 and 60 meters long. Later reconstruction
of Maraapunisaurus as a rebbachisaurid sauropod
dinosaur suggest a
little over 30 meters long. Original vertebrae had a preserved
height of 1.5 meters, possibly being as much as 2.7 meters
high when complete.
Known locations: USA, Colorado - Morrison
Formation.
Time period: Late Jurassic.
Fossil representation: Partial vertebra and femur.
All specimens are now lost, only existing in original illustrations.
Maraapunisaurus
was originally described as a species of the sauropod
dinosaur
Amphicoelias,
and based upon the discovery of a partial vertebra reported to be of
massive proportions, as well as a distal end of a femur that was also
of equally massive proportions. These bones are among the largest
dinosaur fossils ever reported, but there is a problem; they have
vanished and no one knows where they are.
It
would seem quite ridiculous that such large bones should be able to
just disappear, but one detail that we know about them is that they
were fossilised in mudstone, a very weak rock that can be damaged and
eroded easily. We also know that at the time of their original
description in the nineteenth century the fossils were probably not
treated with preservatives to make them hard and resilient (some
palaeontologists did, but others did not, the whole process of
preserving fossils was still in its infancy). It is possibly that
the fossils could have simply crumbled and broken apart after they were
taken from the ground, and this is a theory postulated by Kenneth
Carpenter when he named the Maraapunisaurus genus
in 2018.
Whereas
Amphicoelias was described as a relative to Diplodocus,
and hence a
diplodocid sauropod, Carpenter (2018) considers Maraapunisaurus
to actually be a rebbachisaurid sauropod dinosaur. Rebbachisaurid
sauropods were unknown at the time of the original Amphicoelias
description (the type genus Rebbachisaurus
was named in 1954,
over seventy-five years after Amphicoelias was
named.), and the
2018 naming and assessment of Maraapunisaurus as
a rebbachisaurid
sauropod certainly fits better with the shape of the original
vertebrae. Using the genus Limaysaurus
as a body double (Limaysaurus
is one of the most completely known rebbachisaurids) and scaling the
bones to match the known material for Maraapunisaurus
has also lead to
a reconstructed length of a little over thirty meters, a more
believable estimate.
Further reading
- Maraapunisaurus fragillimus, N.G. (formerly
Amphicoelias
fragillimus), a basal Rebbachisaurid from the Morrison
Formation
(Upper Jurassic) of Colorado. - Geology of the Intermountain
West. 5: 227–244. - Kenneth Carpenter - 2018.
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