Janenschia
Name:
Janenschia
(named after Werner Janensch).
Phonetic: Ya-nen-she-a.
Named By: Rupert Wild - 1991.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda, Titanosauria.
Species: J. robusta (type).
Diet: Herbivore.
Size: Uncertain due to lack of remains, but size
estimates have ranged from 15-24 meters long.
Known locations: Tanzania - Tendaguru Formation.
Time period: Kimmeridgian to Tithonian of the
Jurassic.
Fossil representation: Partial post cranial remains
including vertebrae and limb bones.
Janenschia
is a genus of titanosaur
that has a classification history closely tied
to the African diplodocid sauropod Torneria
and by extension the North
American Barosaurus
and the English Gigantosaurus.
We
start in England in 1869 when Harry Govier Seeley named
Gigantosaurus based upon a few vertebrae, partial
limb bones and an
osteoderm. Fast forward to 1908 and the German palaeontologist
Eberhard Fraas creates a ‘new’ genus of sauropod dinosaur as
Gigantosaurus based upon fossils recovered in
Tanzania in 1907.
Fraas is aware of Seeley’s Gigantosaurus, but
decides to reuse the
name anyway upon the basis that he did not consider Seeley’s
description complete as well as the remains being considered by many
other palaeontologists to be synonymous to other genera. However,
names of animals cannot be used again once an original usage has
been logged, even if it turns out later that that name is a synonym
of another. So in 1911 another German palaeontologist named
Richard Sternfeld renamed the African fossils as Tornieria.
When
Tornieria was established there were two separate
species, the type
species T. africana and a second species T.
robusta (both derived
from G. africana and G. robusta
as originally outlined by
Fraas). In 1922 a further German palaeontologist named Werner
Janensch examined the type species fossils and declared them to be
synonymous with the North American genus Barosaurus.
With the type
species ‘dissolved’, T. robusta could no
longer be classed as
Torneria upon the basis that there was no type
species to refer it
too. It would not be until 1991 however that T.
robusta was
renamed as a new genus named Janenschia by Rupert
Wild.
One
of the things to come to light from the creation of Janenschia
was that
the original fossils first described in 1908 were actually those of
a titanosaur, not a diplodocid sauropod. This realisation meant
that even when Janenschia was known as T.
robusta (and earlier G.
robusta), it was never actually related to T.
africana. This
is why when the Tornieria genus was resurrected in
2006 by Kristian
Remes on the basis of several key differences from Barosaurus
(as
well as appearing on separate continents), Janenschia
remained
separate.
When
Janenschia was created the original species name was retained to create
the new type species, therefore Tornieria robusta
became Janenschia
robusta. The genus name is in honour of Werner Janensch.
Unfortunately Janenschia still remains little
known and further fossil
discoveries of the genus are sorely needed in order to reveal more
detail about this dinosaur.
Further reading
- Janenschia n. g. robusta
(E. Fraas 1908) pro Tornieria
robusta (E. Fraas 1908) (Reptilia, Saurischia,
Sauropodomorpha) [Janenschia n. g. robusta (E. Fraas
1908) for Tornieria robusta (E. Fraas 1908) (Reptilia,
Saurischia, Sauropodomorpha)] - Rupert Wild - 1991.
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