Richardoestesia

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Richardoestesia
Temporal range: Late Cretaceous, 90–66  Ma
O
S
D
C
P
T
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Pg
N
Possible Early Cretaceous (Barremian) records from teeth of the Cedar Mountain Formation, but see [1] .
Richardoestesia.png
Tooth of cf. R. gilmorei with close up of denticles
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Coelurosauria
Genus: Richardoestesia
Currie, Rigby & Sloan, 1990
Type species
Richardoestesia gilmorei
Currie, Rigby & Sloan, 1990
Other species
  • R. isosceles
    Sankey, 2001
  • R. asiatica ? Averianov & Sues, 2013
Synonyms
  • Asiamericana asiatica? Nesov, 1995
  • Ricardoestesia gilmoreiCurrie, Rigby & Sloan, 1990

Richardoestesia is a morphogenus of theropod dinosaur teeth, originally described from the Late Cretaceous of what is now Canada, the United States and Kazakhstan. It currently contains two species, R. gilmorei and R. isosceles, and a possible third, R. asiatica . It has been used as a morphotaxon to describe other theropod teeth widely displaced in time and space from the type species. If all teeth assigned to the genus are truly reflective of the animals biology and taxonomic state, it would have been one of the longest lasting dinosaur genera, perhaps also being the most widely distributed.

History

Tooth of cf. R. isosceles with close up of denticles Richardoestesia isosceles.png
Tooth of cf. R. isosceles with close up of denticles

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. [2] 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. [3]

The genus is named for Richard Estes, to honor his important work [4] on small vertebrates and especially theropod teeth of the Late Cretaceous. The naming authors actually intended to use the spelling Ricardoestesia, Ricardus being the normal latinisation of "Richard". However, except in one overlooked figure caption, the editors of the paper altered the spelling to include the 'h'. [5] Ironically, in 1991 George Olshevsky in a species list also used the spelling Richardoestesia, and indicated Ricardoestesia to be the misspelling, unaware that the original authors actually intended the name to be spelled this way. As a result, under ICZN rules, he acted as "first revisor" choosing between the two spelling variants of the original publication and inadvertently made the misspelt name official. Subsequently, the original authors have adopted the spelling Richardoestesia. The specific name honors Gilmore.

Species

The holotype specimen of Richardoestesia gilmorei (NMC 343) consists of a pair of lower jaws found in the upper Judith River Group, dating from the Campanian age, about 75 million years ago. The jaws are slender and rather long, 193 millimeters, but the teeth are small and very finely serrated with five to six denticles per millimeter. The serration density is a distinctive trait of the species.

In 2001, Julia Sankey named a second species: Richardoestesia isosceles, based on a tooth, LSUMGS 489:6238, from the Texan Aguja Formation, which is of a longer and less recurved type. [6] The teeth of R. isosceles have also been identified as crocodyliform in shape, possibly belonging to a sebecosuchian. [7]

In 2013 a study assumed that the teeth of the coelurosaur Asiamericana asiatica , from the CBI-14 site of the Bissekty Formation in Kazakhstan, [8] were identical to those of Richardoestesia isosceles, and renamed the species into Richardoestesia asiatica. [9] A subsequent study confirmed this in 2019. [10] The holotype of R. asiatica is CCMGE 460/12457, [11] and two other teeth (ZIN PH 1110/ 16 and ZIN PH 1129/16) are also known. [10]

Classification

Referred teeth from the San Juan Basin Richardoestesia teeth.png
Referred teeth from the San Juan Basin

Richardoestesia-like teeth have been found in many Late Cretaceous geological formations, including the Horseshoe Canyon Formation, the Scollard Formation, Hell Creek Formation, Ferris Formation, and the Lance Formation (dated to about 66 million years ago). Similar teeth have been referred to this genus from as early as the Barremian age (Cedar Mountain Formation, 125 million years ago). [1]

Because of the disparity in location and time of the many referred teeth, researchers have cast doubt on the idea that they all belong to the same genus or species, and the genus is best considered a form taxon. A comparative study of the teeth published in 2013 demonstrated that both R. gilmorei and R. isosceles were only definitively present in the Dinosaur Park Formation, dated to between 76.5 and 75 million years ago. R. isosceles was also present in the Aguja Formation, roughly the same age. All other referred teeth most likely belong to different species, which have not been named due to the lack of body fossils for comparison. [12]

Fossils of Richardoestesia have also been found in the Tremp Formation of northeastern Spain (Blasi 2 member). [13]

Paleobiology

Hypothetical life restoration as a dromaeosaur Ojo Alamo cf. Richardoestesia sp profile reconstruction.jpg
Hypothetical life restoration as a dromaeosaur

At least a few studies have speculated a piscivorous lifestyle for Richardoestesia, due to its vast distribution as well as predominance in marine sites. [14] [15]

Related Research Articles

<i>Dromaeosaurus</i> Extinct genus of dinosaurs

Dromaeosaurus is a genus of dromaeosaurid theropod dinosaur that lived during the Late Cretaceous period, sometime between 80 and 69 million years ago, in Alberta, Canada and the western United States. The type species is Dromaeosaurus albertensis, which was described by William Diller Matthew and Barnum Brown in 1922. Its fossils were unearthed in the Dinosaur Park Formation. Teeth attributed to this genus have been found in the Prince Creek Formation. Dromaeosaurus is the type genus of both Dromaeosauridae and Dromaeosaurinae, which include many genera with similar characteristics to Dromaeosaurus such as possibly its closest relative Dakotaraptor. Dromaeosaurus was heavily built, more so than other dromaeosaurs that are similar in size, like Velociraptor.

<i>Saurornitholestes</i> Extinct genus of dinosaurs

Saurornitholestes is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States.

<i>Chirostenotes</i> Extinct genus of dinosaurs

Chirostenotes is a genus of oviraptorosaurian dinosaur from the late Cretaceous of Alberta, Canada. The type species is Chirostenotes pergracilis.

<i>Montanoceratops</i> Extinct genus of dinosaurs

Montanoceratops is an extinct genus of small ceratopsian dinosaur that lived approximately 70 million years ago during the latter part of the Cretaceous Period in what is now Montana and Alberta. Montanoceratops was a small sized, moderately-built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 2.5 m (8.2 ft) in length and 170 kg (370 lb) in body mass.

<i>Hagryphus</i> Extinct genus of dinosaurs

Hagryphus is a monospecific genus of caenagnathid dinosaur from southern Utah that lived during the Late Cretaceous in what is now the Kaiparowits Formation of the Grand Staircase–Escalante National Monument. The type and only species, Hagryphus giganteus, is known only from an incomplete but articulated left manus and the distal portion of the left radius. It was named in 2005 by Lindsay E. Zanno and Scott D. Sampson. Hagryphus has an estimated length of 2.4–3 metres and weight of 50 kilograms.

Asiaceratops is a genus of herbivorous ceratopsian dinosaur. It lived during the Early-Late Cretaceous. The type species, A. salsopaludalis is known from Uzbekistan, while A. sulcidens is known from China and Mongolia.

<i>Zapsalis</i> Extinct genus of dinosaurs

Zapsalis is a genus of dromaeosaurine theropod dinosaurs. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include teeth but no other remains.

<i>Paronychodon</i> Extinct genus of dinosaurs

Paronychodon was a theropod dinosaur genus. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include "buckets" of teeth from many disparate times and places but no other remains, and should be considered a form taxon.

Asiamericana is a dubious genus of coelurosaur known only from isolated teeth found in the Bissekty Formation of Uzbekhistan. It was named to recognize the occurrence of similar fossil teeth in Central Asia and North America. These regions once formed a connected land mass, during the Cretaceous period.

<span class="mw-page-title-main">Dinosaur Park Formation</span> Uppermost member of the Belly River Group geologic unit in Alberta, Canada

The Dinosaur Park Formation is the uppermost member of the Belly River Group, a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 76.5 and 74.4 million years ago. It was deposited in alluvial and coastal plain environments, and it is bounded by the nonmarine Oldman Formation below it and the marine Bearpaw Formation above it.

<i>Elmisaurus</i> Extinct genus of dinosaurs

Elmisaurus is an extinct genus of caenagnathid dinosaur from the Late Cretaceous Nemegt Formation of Mongolia. It was a theropod belonging to the Oviraptorosauria.

<i>Euronychodon</i> Extinct genus of dinosaurs

Euronychodon is the name given to a genus of coelurosaur dinosaur from the Late Cretaceous of Europe and Asia. Euronychodon is known from teeth only. These are similar to those of another coelurosaur tooth genus, Paronychodon.

<span class="mw-page-title-main">Horseshoe Canyon Formation</span> Geological formation in Canada

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.

<span class="mw-page-title-main">Caenagnathidae</span> Extinct family of dinosaurs

Caenagnathidae is a family of derived caenagnathoid dinosaurs from the Cretaceous of North America and Asia. They are a member of the Oviraptorosauria, and relatives of the Oviraptoridae. Like other oviraptorosaurs, caenagnathids had specialized beaks, long necks, and short tails, and would have been covered in feathers. The relationships of caenagnathids were long a puzzle. The family was originally named by Raymond Martin Sternberg in 1940 as a family of flightless birds. The discovery of skeletons of the related oviraptorids revealed that they were in fact non-avian theropods, and the discovery of more complete caenagnathid remains revealed that Chirostenotes pergracilis, originally named on the basis of a pair of hands, and Citipes elegans, originally thought to be an ornithomimid, named from a foot, were caenagnathids as well.

<span class="mw-page-title-main">Aguja Formation</span>

The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. Fossil palms have also been unearthed here.

The Bostobe Formation is a geological formation in Qaraghandy & Qyzylorda, Kazakhastan whose strata date back to the Late Cretaceous.

The Nichkesaisk or Nichkesai Formation is an early Campanian geologic formation in Kyrgyzstan. Fossil dinosaur eggs have been reported from the formation.

The Ialovachsk or Yalovach Formation is a geologic formation in Kyrgyzstan, Tajikistan and Uzbekistan dating to the Santonian age of the Cretaceous period.

Continuoolithus is an oogenus of dinosaur egg found in the late Cretaceous of North America. It is most commonly known from the late Campanian of Alberta and Montana, but specimens have also been found dating to the older Santonian and the younger Maastrichtian. It was laid by an unknown type of theropod. These small eggs are similar to the eggs of oviraptorid dinosaurs, but have a distinctive type of ornamentation.

<i>Leptorhynchos gaddisi</i> Extinct species of dinosaur

Leptorhynchos is an extinct genus of caenagnathid theropod from the Late Cretaceous of what is now the US state of Texas, although it has been suggested to also exist in Alberta and South Dakota. The type species is L. gaddisi, and it is currently the only widely accepted valid species. The generic name of Leptorhynchos comes from the Greek "leptos" meaning "small" and "rhynchos" meaning "beak". The specific epithet is in honor of the Gaddis family, who owned the land on which the holotype was discovered.

References

  1. 1 2 Kirkland, Lucas and Estep, (1998). "Cretaceous dinosaurs of the Colorado Plateau." in Lucas, Kirkland and Estep (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin, 14, 79-89.
  2. Gilmore, C.W., 1924, "A new coelurid dinosaur from the Belly River Cretaceous of Alberta", Canada Department of Mines Geological Survey Bulletin (Geological Series)38(43): 1-12
  3. Currie, P. J., K. J. Rigby, and R. E. Sloan. 1990. "Theropod teeth from the Judith River Formation of southern Alberta, Canada". Pp. 107–125. In P. J. Currie, and K. Carpenter, eds. Dinosaur Systematics: Perspectives and Approaches. Cambridge University Press, Cambridge.
  4. Estes, R., 1964, Fossil vertebrates from the Late Cretaceous Lance Formation, eastern Wyoming. University of California Publications in Geological Sciences 49: 1-180
  5. Archived 2016-08-06 at the Wayback Machine
  6. J.T. Sankey, 2001, "Late Campanian southern dinosaurs, Aguja Formation, Big Bend, Texas", Journal of Paleontology75(1): 208-215
  7. Company, J.; Suberbiola, X.P.; Ruiz-Omenaca, J.I.; Buscalioni, A.D. (2005). "A new species of Doratodon (Crocodyliformes: Ziphosuchia) from the Late Cretaceous of Spain" (PDF). Journal of Vertebrate Paleontology. 25 (2): 343–353. doi:10.1671/0272-4634(2005)025[0343:ANSODC]2.0.CO;2.
  8. Nessov, L. A. (1995). Dinozavri severnoi Yevrasii: Novye dannye o sostave kompleksov, ekologii i paleobiogeografii [Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography], Scientific Research Institute of the Earth's Crust, St. Petersburg State University, St. Petersburg, Russia: 156 pp. + 14 pl. [in Russian with short English, German, and French abstracts].
  9. Sues H.D. and Averianov, A. (2013). "Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous (Cenomanian–Turonian) of Uzbekistan". Canadian Journal of Earth Sciences. 50: 306-314
  10. 1 2 Alexander Averianov & Hans-Dieter Sues. (2019). "Morphometric analysis of the teeth and taxonomy of the enigmatic theropod Richardoestesia from the Upper Cretaceous of Uzbekistan". Journal of Vertebrate Paleontology: e1614941
  11. Nessov, L. A. (1995). Dinozavri severnoi Yevrasii: Novye dannye o sostave kompleksov, ekologii i paleobiogeografii [Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography], Scientific Research Institute of the Earth's Crust, St. Petersburg State University, St. Petersburg, Russia: 156 pp. + 14 pl. [in Russian with short English, German, and French abstracts].
  12. Larson DW, Currie PJ (2013) Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time. PLoS ONE 8(1): e54329. doi:10.1371/journal.pone.0054329
  13. Blasi 2 at Fossilworks.org
  14. Gerardo Carbot-Chanona, Héctor E. Rivera-Sylva, Presence of a maniraptoriform dinosaur in the Late Cretaceous (Maastrichtian) of Chiapas, Southern Mexico, December 2011Boletin de la Sociedad Geologica Mexicana 63(3):393-398 Follow journal DOI: 10.18268/BSGM2011v63n3a2
  15. Longrich, N., 2008, Small theropod teeth from the Lance Formation of Wyoming, USA, in Sankey, J.T., Baszio, S. (eds.), Vertebrate microfossil assemblages: their role in paleoecology and paleobiogeography: Bloomington, Indiana, Indiana University Press, 135-158. (5) (PDF) Presence of a maniraptoriform dinosaur in the Late Cretaceous (Maastrichtian) of Chiapas, Southern Mexico. Available from www.researchgate.net [accessed March 14, 2021].

Further reading