Name Meaning: Richard Estes lizard
Geologic Era: Late Cretaceous
Location Discovered: Judith River Formation (possibly other formations as well)
Size: Small (less that 1 meter long)
Estimated Range: Modern Northwest America
Extinction Date: 65 million years ago (K-T event)
Richardoestesia is a bit of a mystery, as we have little fossil remains for it. What we do have are primarily teeth with possible lower jaw material. Two species have been identified, R. gilmorei and R. isosceles. Based on conformation, this tooth belongs to the latter. Paleontological staff at Chicago’s Field Museum put this tooth under a microscope to look at the serrations, which allowed me to revise my original identification of the species. The density of the serrations is characteristic of these species, with 5 or 6 present per millimeter.
What Richardoestesia looked like will not be known until more skeletal material is found. The lower jaws that were unearthed are very slender, which would fit with the tooth size. It is possible that Richardoestesia will be classified as either dromaeosaurid or troodontid. If it is a dromaeosaur, it is a very small and lightly built one. Troodontid would, in my opinion, fit the tooth and jaw shape better. Whatever the ultimate classification, Richardoestesia was a widespread animal, with teeth being found all over the western United States.
As one can see, our tooth bears much more of a resemblance to R. isosceles than R. gilmorei. These serrations would have been very useful for cutting apart prey, which for Richardoestesia would have been rather small. Richardoestesia probably preyed on small animals such as mammals, lizards, and possibly baby dinosaurs.
R. gilmorei Tooth:”Richardoestesia” by Derek W. Larson, Philip J. Currie – http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0054329. Licensed under CC BY 2.5 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Richardoestesia.png#/media/File:Richardoestesia.png
R. isosceles tooth:”Richardoestesia isosceles” by Derek W. Larson, Philip J. Currie – http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0054329. Licensed under CC BY 2.5 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Richardoestesia_isosceles.png#/media/File:Richardoestesia_isosceles.png
Life Reconstruction: https://www.deviantart.com/teratophoneus/art/Richardoestesia-gilmorei-284115686
Referred lower jaw: http://www.paleofile.com/Dinosaurs/Theropods/Ricardoestesia.asp