Richardoestesia
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''Richardoestesia'' is a morphogenus of
theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...
dinosaur teeth, originally described from the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
of what is now
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
and
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
. 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 (as some teeth go as far back as the Late Jurassic), it would have been one of the longest lasting dinosaur genera, perhaps also being the most widely distributed.


History

The jaws were found in 1917 by
Charles Hazelius Sternberg Charles Hazelius Sternberg (June 15, 1850 – July 20, 1943) was an American fossil collector and paleontology, paleontologist. He was active in both fields from 1876 to 1928, and collected fossils for Edward Drinker Cope and Othniel C. Marsh, ...
and sons in the
Dinosaur Provincial Park Dinosaur Provincial Park is a UNESCO World Heritage Site situated 220 kilometres (137 mi) east of Calgary, Alberta, Canada; or northeast of Brooks. The park is situated in the Red Deer River valley, which is noted for its striking badland topo ...
in
Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
at the Little Sandhill Creek site. In 1924
Charles Whitney Gilmore Charles Whitney Gilmore (March 11, 1874 – September 27, 1945) was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum (now the N ...
named ''
Chirostenotes ''Chirostenotes'' ( ; named from Ancient Greek, Greek 'narrow-handed') is a genus of oviraptorosaurian dinosaur from the late Cretaceous (about 76.5–75 million years ago) of Alberta, Canada. The type species is ''Chirostenotes pergracilis''. ...
pergracilis'' and referred the jaws to this species. In the 1980s it became clear that ''Chirostenotes'' was an
oviraptorosaur Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or wi ...
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 Richard Estes (born May 14, 1932, in Kewanee, Illinois) is an American artist, best known for his photorealist paintings. The paintings generally consist of reflective, clean, and inanimate city and geometric landscapes. He is regarded as one of ...
, 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'', ''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'. 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 The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...
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 Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
honors Gilmore.


Species

The
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
specimen of ''Richardoestesia gilmorei'' (NMC 343) consists of a pair of lower jaws found in the upper Judith River Group, dating from the
Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...
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 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 ...
, which is of a longer and less recurved type. The teeth of ''R. isosceles'' have also been identified as
crocodyliform Crocodyliformes is a clade of Crurotarsi, crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the ...
in shape, possibly belonging to a sebecosuchian. In 2013 a study assumed that the teeth of the
coelurosaur Coelurosauria (; from Greek, meaning "hollow-tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, ty ...
'' Asiamericana asiatica'', from the CBI-14 site of the
Bissekty Formation The Bissekty Formation (sometimes referred to as Bissekt) is a formation (geology), geologic formation and Lagerstätte which outcrop, crops out in the Kyzyl Kum desert of Uzbekistan, and dates to the Late Cretaceous Period (geology), Period. Laid ...
in
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
,in Russian with short English, German, and French abstracts were identical to those of ''Richardoestesia isosceles'', and renamed the species into ''Richardoestesia asiatica''. A subsequent study confirmed this in 2019. The holotype of ''R. asiatica'' is CCMGE 460/12457, and two other teeth (ZIN PH 1110/ 16 and ZIN PH 1129/16) are also known.


Classification

''Richardoestesia''-like teeth have been found in many Late Cretaceous geological formations, including the
Horseshoe Canyon Formation 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. The Horseshoe Canyon Formation is part of th ...
, the
Scollard Formation The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it inc ...
,
Hell Creek Formation The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The Formation (stratigraphy), formation s ...
,
Ferris Formation The Ferris Formation is a Late Cretaceous (~66 Ma) to Paleocene (66-63 Ma), fluvial-deltaic geological formation in southern Wyoming. It contains a variety of trace and body fossils, preserved in sandy fluvial channel deposits and overbank units. ...
, and the
Lance Formation The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69–66 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the lates ...
(dated to about 66 million years ago). Similar teeth have been referred to this genus from as early as the
Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...
age (
Cedar Mountain Formation The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain (Utah), Cedar Mountain in northern Emery Cou ...
, 125 million years ago). 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 Form classification is the classification of organisms based on their morphology (biology), morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncer ...
. 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 The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 7 ...
, dated to between 76.5 and 75 million years ago. ''R. isosceles'' was also present in the
Aguja Formation 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 ...
, 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. Fossils of ''Richardoestesia'' have also been found in the
Tremp Formation The Tremp Formation (, ), alternatively described as Tremp Group (), is a geological Formation (geology), formation in the comarca Pallars Jussà, Lleida Province, Lleida, Spain. The formation is restricted to the Tremp-Graus Basin, Tremp or T ...
of northeastern Spain (Blasi 2 member). The oldest fossils that have been referred to ''Richardoestesia'' come from the Jurassic of Portugal.


Paleobiology

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


References


Further reading

* *


External links

*
The "''Ricardoestesia'' typo" is described


{{Portal bar, Dinosaurs, Paleontology Coelurosauria Dinosaur genera Late Cretaceous dinosaurs Dinosaur Park Formation Bissekty Formation Taxa named by Philip J. Currie Fossil taxa described in 1990 Dinosaurs of North America Dinosaurs of Asia