Histology and Geochemistry of Allosaurus (Dinosauria: Theropoda) From the Cleveland-Lloyd Dinosaur Quarry (Late Jurassic, Utah): Paleobiological Implications

• Published in: Frontiers in earth science (Lausanne) Vol. 9
• Main Authors: Ferrante, Christophe, Cavin, Lionel, Vennemann, Torsten, Martini, Rossana
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 07-04-2021
• Subjects: femur; growth; Morrison Formation; skeletal maturity; tibia
• ISSN: 2296-6463; 2296-6463
• DOI: 10.3389/feart.2021.641060

The Late Jurassic
Allosaurus
is one of the better-studied dinosaurs. A histological and geochemical study of a tibia and a femur of
A. fragilis
recovered in the Upper Jurassic Cleveland-Lloyd Dinosaur Quarry, Utah, United States has been done in order to address growth characteristics of this species. The two bones, probably belonging to separate individuals, are among the largest known for this species, which make them suitable to address such issues. The inclusion of our data on femur growth markings in the previously published data reflects a range of growth variability rather than two distinct growth strategies. The tibia has a well-developed external fundamental system indicating somatic maturity achievement. Using a quantitative method of superimposition to retrocalculate missing lines of arrested growth, the tibia appears to correspond to an individual that reached its skeletal maturity at 22 years and died at approximately 26 years. In the tibia, the concentration of zinc, a potential biomarker associated with bone formation, displays a higher concentration in zones of rapid growth compared to annuli. There is no direct relationship between the values of δ
18
O
p
and the lines of arrested growth distribution. The absence of relations between the histological organization and an enrichment in REE of the bone, indicates that the variations of δ
18
O
p
likely represent a diagenetic process rather than a primordial, biologic composition. However, the geochemical composition of the bones is not homogeneous along the sections, indicating that the signal variations have not been completely erased by diagenesis.