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a plant-eating iguanodont dinosaur from the Early Cretaceous of North America and Canada.
Pronunciation: teh-NON-toe-SOR-us
Meaning: Tendon lizard
Author/s: John Ostrom (1970)
Synonyms: None known
First Discovery: Montana, USA
Chart Position: 178

Tenontosaurus tilletti

Despite its size, seven meters long and a ton in weight, Tenontosaurus had two glaring weaknesses; like all herbivorous dinosaurs it was as dim as a miner's boot and like most if not all ornithopods it lacked any form of protective armour. But was it a sitting duck, or sitting duck-billed dinosaur? Was it even a duck-billed dinosaur? Well... no, no, and no.

Tenontosaurus was originally assigned to Hypsilophodontidae, a family of herbivorous dinosaurs which has been disbanded (no point having a "family" with only one member; Hypsilophodon) so it now loiters at the foot of Iguanodontia as one of its most primitive members. It was first discovered by an AMNH expedition to Big Horn County in 1903, but despite a colossal haul of remains during the 1930s it wasn't afforded much attention until John Ostrom of the Yale Peabody Museum set up a full time digsite at the Big Horn Basin in the 1960's, and it was officially named in 1970.

Tenontosaurus appears to have been a favourite prey of Deinonychus, or at least its scavenge-meat of choice, as the pack-hunting raptor's teeth have been found alongside 20% of all known Tenontosaurus remains, compared to virtually none of the same area's other herbivores. It's a bit unfortunate that this unassuming quadrupedal plant muncher's fame arrived via what it was eaten by rather than an array of star-spangled characteristics of its own, though it does have one, rather large, unique feature...

At almost the same length as the rest of its body and bigger than any other dinosaur relative to body size, its tail was thick and deep and required a series of heavyweight tendons just to keep it off the floor. In theory it could have dealt a knockout blow if executed with anything resembling precision and this was their only form of defence, barring "safety in numbers".

Tenontosaurus was the cow of the cretaceous, relentlessly moving in herds to find fodder for their huge batteries of teeth and if the weak, injured or old became tail-end-Charlies and easy prey for predators, tough luck. This may sound heartless but it ensured survival of the fittest and if you were a herbivore during the early cretaceous you needed to be fit no matter how big you or your tail were.
(Tillet's tendon lizard)Etymology
Tenontosaurus is derived from the Greek "ténontas" (tendon) and "sauros" (lizard") in reference to the system of stiffening tendons in its back and tail. Barnum Brown unofficially named "Tenantosaurus" (with an "a") in the 1930's but it didn't receive its official name, "Tenontosaurus (with an "o"), until a full description by John Ostrom in 1970.
The species epithet, tilletti, honors the Lloyd Tillet family of Lovell, Wyoming. George Olshevsky pleaded with the ICZN to have this epithet changed to the correct "tilletorum" (it honors a family and plural endings are "-orum", singular are "-i") but to no avail.
The first remains of Tenontosaurus were found in the Himes Member of the Cloverly Formation, Wheatland County, Montana, USA, by a Barnum Brown-led American Museum of Natural History (AMNH) expedition in 1903. More discoveries were made in the 1930s, 1940s and 1960s. The holotype (AMNH 3040) is a partial skeleton.
Era: Mesozoic
Epoch: Early Cretaceous
Stage: Aptian
Age range: 120-110 mya
Est. max. length: 7 meters
Est. max. hip height: 2 meters
Est. max. weight: 1.2 tons
Diet: Herbivore
Family Tree:
Second Species
Tenontosaurus dossi, discovered in what appears to be a dried-up lagoon, was described by Winkler, Murray, and Jacobs in 1997. It's older and more primitive than Tenontosaurus tilletti, and perhaps the most primitive iguanodontian of all.
• J. H. Ostrom (1970) "Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana". Peabody Museum Bulletin 35:1-234.
• Winkler, Dale A, Phillip A Murry and Louis L Jacobs (1997) "A New Species of Tenontosaurus (Dinosauria: Ornithopoda) from the Early Cretaceous of Texas".
• Brian T. Roach and Daniel L. Brinkman (2007) "A Reevaluation of Cooperative Pack Hunting and Gregariousness in Deinonychus antirrhopus and Other Nonavian Theropod Dinosaurs".
• D. Andrew Thomas (2015) "The cranial anatomy of Tenontosaurus tilletti Ostrom, 1970 (Dinosauria, Ornithopoda)".
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To cite this page:
Atkinson, L. "TENONTOSAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 21st Feb 2018.