The ‘star’ of this first installment is a tibia (shin bone) from the Jurassic, meat-eating Theropod, Elaphrosaurus ("lightweight lizard"). What we know about Elaphrosaurus comes from one near-complete but headless skeleton found in Tanzania.

This dinosaur was about 20 ft long, just under 5 ft high at the hip, and quite light for its size. The tibia was also found to be much longer than the femur: a clue that Elaphrosaurus was probably a very fast, agile runner.

Concrete Jungle. The Elaphrosaurus tibia is from the Bone Bed Unit in a hill adjacent to the main digsite area that we call the ‘concrete jungle’. The nickname of this desolate dig zone fits because the matrix in the hill is extremely hard.

The bone was discovered in a pile-up of bones from many species, which included some of the rarer dinosaur remains  - such as Ankylosaurus bones, an unknown Theropod jaw and Barosaurus cervical vertebrae. No other Elaphrosaurus bone has been found at the digsite.

Unusual Shape. In the field the tibia looked much like a rib section to its discoverer, Bob Simon, as it was encased in a hard sandstone matrix. During preparation, however, it became obvious to him that it was not a rib but something quite different.

After exposing the ends, he saw that it was a tibia, somewhat compressed and crushed along the  shaft. But it was also very slender, very straight and very hollow.

Definitive ID. Bob researched Jurassic Theropods to identify the species. When his hunt turned up nothing, he sent images to vertebrate paleontologists. Certain attributes, such as the bone ends and its shape, size and hollow nature, led them to the ID of Elaphrosaurus.

Go to Bones & Teeth Gallery.

Another Bone Zone: The Mystery Theropod Jaw