Name means: Lambeosaurs' Dawn
Range: Early Cretaceous (Albian ,105-100 MYA) from Utah
Size estimate: 20-25 ft length, 2-2.5 tons
Discovery: James Kirkland, 1998
Classification: dinosauria, ornithischia, ornithopoda, iguanodontia, hadrosauroidea
The Cedar Mountain Formation of Utah—Eolambia’s old stomping grounds—holds far more secrets that await discovery. At the 2017 annual meeting of the Utah Friends of Paleontology, Utah’s state paleontologist Jim Kirkland said that an estimated 10-12 species new to science have been uncovered from the formation, though they have not yet received names and formal descriptions. Future expeditions will likely uncover many more.
The Cedar Mountain Formation represents the best picture of Early Cretaceous ecology in North America. This is due in part to the dryness of the ancient climate and the resulting excellent preservation of fossils, and the degree of exposure of those rocks in the modern geology.
For Further Reading:
Kirkland, J. I. (1998). A new hadrosaurid from the upper Cedar Mountain Formation (Albian-Cenomanian: Cretaceous) of eastern Utah–the oldest known hadrosaurid (lambeosaurine?). New Mexico Museum of Natural History and Science Bulletin, 14, 283-295.
McDonald, A. T., Bird, J., Kirkland, J. I., & Dodson, P. (2012). Osteology of the basal hadrosauroid Eolambia caroljonesa (Dinosauria: Ornithopoda) from the Cedar Mountain Formation of Utah. PLoS One, 7(10), e45712.
When Utah's state paleontologist Jim Kirkland first described Eolambia, details of the incomplete skull led him to conclude it was an early member of the crested duckbill group, the lambeosaurs. Later finds proved Eolambia's design did not have all the features of the hadrosaurs. It even had a small thumb spike like Camptosaurus and Iguanodon. Later duckbill dinosaurs lacked the thumb spike.
Eolambia does seem closely related to the duckbills, though. It shares many features with them that earlier iguanodontids lack. Where older members of the group have narrow snouts, Eolambia has a broader snout. This design implies that Eolambia could eat a wider range of foods than its older relatives. It also suggests that the flora of western North America was changing. Herbivores that could eat a greater variety of plants gained the advantage. Fossils from Eastern Utah help support this explanation. Eolambia's fossils occur in some of the same rocks as the iguanodontid Tenontosaurus. You can see Tenontosaurus portrayed nearby. Tenontosaurus bones show up in the older layers, while Eolambia's become more common in younger layers. This trend may indicate the replacement of a selective herbivore like Tenontosaurus with the generalist Eolambia.