Richardoestesia
A morphogenus of theropod teeth spanning vast time and space.
Richardoestesia is a genus of theropod dinosaur known only from teeth, first identified in Late Cretaceous rocks found in what is now Canada, the United States, and possibly Uzbekistan. The genus includes one widely accepted species—R. gilmorei—and a possible second, R. asiatica, though this last has also been placed in its own genus, Asiamericana. Because the name has been applied as a morphotaxon to theropod teeth from very different times and places, some of which date back to the Late Jurassic, the genus would rank among the longest-lived dinosaur groups if all those teeth truly belong to it, and it might also be the most widespread. However, teeth from the Jurassic of Portugal are not widely accepted as belonging to this genus, so Richardoestesia is currently considered a Late Cretaceous genus only.
The first fossils were a pair of lower jaws found in 1917 by Charles Hazelius Sternberg and his sons at Little Sandhill Creek in Alberta’s Dinosaur Provincial Park. In 1924, Charles Whitney Gilmore named the species Chirostenotes pergracilis and assigned the jaws to it. By the 1980s, it was clear that Chirostenotes was an oviraptorosaur, which could not have had such long jaws, so in 1990 Phillip Currie, John Keith Rigby, and Robert Evan Sloan gave the jaws their own name: Richardoestesia gilmorei. The genus honors Richard Estes for his work on small Late Cretaceous vertebrates, especially theropod teeth. The authors originally intended the spelling Ricardoestesia (from Ricardus, the standard Latin form of “Richard”), but the journal’s editors changed it to include an “h” in all but one figure caption. In 1991, George Olshevsky, unaware of the authors’ intent, listed the species as Richardoestesia and treated Ricardoestesia as a misspelling, thereby acting as the “first revisor” under ICZN rules and making the altered spelling official. The authors later adopted that spelling themselves. The species name honors Gilmore.
The holotype of R. gilmorei (NMC 343) consists of a pair of lower jaws from the upper Judith River Group, dating to the Campanian stage about 75 million years ago. The jaws are slender and long—193 millimeters—but the teeth are small and very finely serrated, with five to six denticles per millimeter, a distinctive trait. In 2001, Julia Sankey named a second species, R.
Quick Facts
- Taxon
- Richardoestesia
- Type Species
- Richardoestesia gilmorei
- Type Species Authority
- Currie, Rigby & Sloan, 1990
Facts from the source article.
Lore & Background
The jaws were found in 1917 by Charles Hazelius Sternberg and sons in the Dinosaur Provincial Park in Alberta at the Little Sandhill Creek site. In 1924 Charles Whitney Gilmore named Chirostenotes pergracilis and referred the jaws to this species. In the 1980s it became clear that Chirostenotes was an oviraptorosaur to which the long jaws could not have belonged. Therefore, in 1990 Phillip Currie, John Keith Rigby and Robert Evan Sloan named a separate species: Richardoestesia gilmorei. The genus is named for Richard Estes, to honor his important work on small vertebrates and especially theropod teeth of the Late Cretaceous. The naming authors actually intended to use the spelling Ricardoestesia, but editors altered it to include the 'h'. In 1991 George Olshevsky used the spelling Richardoestesia and indicated Ricardoestesia to be the misspelling, inadvertently making the misspelt name official under ICZN rules.
Reader's Guide
Richardoestesia is significant primarily as a morphotaxon for isolated theropod teeth, making it a tool for paleobiogeographic and biostratigraphic studies rather than a traditional genus. Its teeth have been found across North America, Europe, and Asia, from the Late Jurassic of Portugal to the latest Cretaceous of the Hell Creek Formation. However, a 2013 study demonstrated that only R. gilmorei and R. isosceles are definitively present in the Dinosaur Park Formation (76.5–75 million years ago), with R. isosceles also in the Aguja Formation. All other referred teeth likely belong to different, unnamed species due to the lack of body fossils for comparison. This uncertainty highlights the limitations of tooth-based taxonomy. The genus also illustrates the quirks of taxonomic nomenclature, as the intended spelling Ricardoestesia was accidentally made unofficial by a later author. At least a few studies have speculated a piscivorous lifestyle for Richardoestesia, based on its vast distribution and predominance in marine sites.
Did You Know?
- The teeth of R. isosceles have been identified as crocodyliform in shape, possibly belonging to a sebecosuchian.
- The oldest fossils referred to Richardoestesia come from the Jurassic of Portugal.
- The intended spelling Ricardoestesia was accidentally made unofficial by George Olshevsky in 1991, who acted as 'first revisor' under ICZN rules.
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