Tenontosaurus
Name: Tenontosaurus
(Sinew lizard).
Phonetic: Te-non-to-sore-us.
Named By: John Ostrom - 1970.
Classification: Chordata, Reptilia, Dinosauria,
ornithoschia, Cerapoda, Ornithopoda.
Species: T. tiletti (type),
T.dossi.
Diet: Herbivore.
Size: 6.5 to 8 meters long.
Known locations: Western North America.
Time period: Aptian to Albian of the Cretaceous.
Fossil representation: Many specimens of both
species have been recovered, although T.tilletti
is the more common.
Perhaps
the
most striking feature of Tenontosaurus is the tail
which actually takes
up more than half the total body length. This tail was supported by a
network of strong tendons which ensured it was always carried erect off
the ground. It is in reference to these tendons that Tenontosaurus
was given its name in 1970. However the first Tenontosaurus
remains
were discovered in 1903, and later it was given the informal name
of 'Tenantosaurus' by Barnum Brown. Because this
name was informal it
is not regarded as a synonym, and the re-spelled version of
Tenontosaurus by John Ostrom is now its
scientifically recognised name.
Over
the years there have
been over sixty specimens of Tenontosaurus
recovered, strongly
suggesting that it would have been a common sight during the Aptian and
Albian periods of the Cretaceous. Many of these remains also have
preserved fossils of the carnivorous dinosaur Deinonychus,
especially
the teeth of these predators. One fossil site also has five
Deinonychus individuals fossilised in close
proximity to the remains of
a Tenontosaurus. This has been interpreted as
evidence of pack
hunting in these dinosaurs although it is by no means conclusive proof.
Study
of the fossil sites and
the periods they come from has brought the suggestion that
Tenontosaurus could adapt to life in different kinds
of environments.
The start of the Albian period was known for its arid conditions,
but as time progressed it steadily grew wetter into a tropical climate
featuring river deltas and swamps during the wet seasons to a savannah
climate during the dry. Despite these changing climates,
Tenontosaurus continued to thrive as evidenced from
its numerous
remains in the fossil record.
As
a dinosaur Tenontosaurus
was once classed as a hypsilophdontid until that group was
restructured, the result of which has seen Tenontosaurus
now
classified as a primitive iguanodont. Because
of its long forelimbs
and strong finger bones, it seems that Tenontosaurus
was primarily
quadrupedal. It is however likely that the long tail would have
worked as an effective counterbalance, allowing Tenontosaurus
to rear
up on its hind legs to reach a greater range of plant material that
would have been out of reach of other low browsers. Tenontosaurus
is one of many
dinosaurs to have medullary bone tissue found on their femurs. Study
of other specimens suggests that these dinosaurs were able to reproduce
before they were fully grown.
Further reading
- Stratigraphy and paleontology of the Cloverly Formation (Lower
Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Peabody
Museum Bulletin 35:1-234. - J. H. Ostrom - 1970.
- The paleoecology of the ornithopod dinosaur Tenontosaurus tilletti
from the Cloverly Formation, Big Horn Basin of Wyoming and Montana. -
The Mosasaur, 2: 151–163. - C. A. Foster - 1984.
- Taphonomy and paleobiological implications of
Tenontosaurus-Deinonychus associations. - Journal of Vertebrate
Paleontology. 15 (4): 707–712. - W. D. Maxwell & J. H. Ostrom -
1995.
- A new species of Tenontosaurus (Dinosauria: Ornithopoda) from the
Early Cretaceous of Texas. - Journal of Vertebrate Paleontology
17(2):330-348. - D. A. Winkler, P. A. Murry & L. L. Jacobs -
1997.
- The Ontogenetic Osteohistology of Tenontosaurus tilletti. - PLoS ONE.
7 (3): e33539. - S. Werning (Andrew A. Farke, ed.) - 2012.
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