Technosaurus
Encyclopedia
Technosaurus (meaning "(Texas
) Tech lizard") is an extinct genus
of Late Triassic
archosauriform
, perhaps a dinosauriform
similar to Silesaurus
, from the Norian
age Upper Triassic Bull Canyon Formation (Dockum Group
) of Texas
. For about 20 years after its description, it was thought to be a basal
ornithischia
n dinosaur
, but better remains of other Triassic archosaurs have cast doubt on this interpretation. As named, it was a chimera
of different animals.
TTUP
P9021, which initially consisted of a premaxilla
(tip of the upper jaw), two lower jaw pieces, a back vertebra, and an astragalus
. Technosaurus and its type species
, T. smalli, were named by Sankar Chatterjee
in 1984. He described it as a fabrosaurid
, a clade
of small early ornithischians now considered to have been an artificial grouping. Material from the quarry where P9021 was found is disassociated and comes from a variety of Late Triassic animals,
which would prove problematic.
The genus was reviewed in 1991 by Paul Sereno
, who interpreted the premaxilla and a fragment from the front of the lower jaw as pertaining to a hatchling prosauropod, and found the vertebra to be indeterminate and the astragalus an unidentifiable fragment. Thus, he restricted the remains to be considered Technosaurus to the second lower jaw piece, a posterior
fragment. It was further reviewed in the light of new remains that spurred reevalutation of purported Triassic dinosaurs, particularly ornithischians named from tooth or jaw material. Irmis et al. (2007) agreed with the removal of the vertebra and astragalus, but found no characteristics that were unambiguously dinosaurian in the skull fragments. They noted similarities to Silesaurus in the jaw fragments Sereno had excluded, and themselves excluded the posterior fragment as actually belonging to the unusual rauisuchia
n Shuvosaurus
. These authors would later restate their case, concluding that Technosaurus, defined only by the premaxilla and non-Shuvosaurus lower jaw fragment, was a valid, diagnostic genus, but could not be definitely classified beyond Archosauriformes
incertae sedis
, and was unlikely to be either an ornithischian or sauropodomorph
dinosaur.
Texas Tech University
Texas Tech University, often referred to as Texas Tech or TTU, is a public research university in Lubbock, Texas, United States. Established on February 10, 1923, and originally known as Texas Technological College, it is the leading institution of the Texas Tech University System and has the...
) Tech lizard") is an extinct genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
archosauriform
Archosauriformes
Archosauriformes is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Late Permian...
, perhaps a dinosauriform
Dinosauriformes
Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs, and an at least partially perforated acetabulum, the hole in the hip socket traditionally used...
similar to Silesaurus
Silesaurus
Silesaurus is a genus of dinosauriform from the Late Triassic, approximately 230 million years ago in the Carnian faunal stage of what is now Poland....
, from the Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
age Upper Triassic Bull Canyon Formation (Dockum Group
Dockum Group
The Dockum is a Late Triassic geologic group found primarily on the Llano Estacado of western Texas and eastern New Mexico with minor exposures in southwestern Kansas, eastern Colorado, and Oklahoma panhandle. The Dockum reaches a maximum thickness of slightly over 650 m but is usually much...
) of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. For about 20 years after its description, it was thought to be a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
, but better remains of other Triassic archosaurs have cast doubt on this interpretation. As named, it was a chimera
Chimera (paleontology)
In paleontology, a chimera is a fossil which was reconstructed with elements coming from more than a single species of animal. A now classic example of chimera is Protoavis.-List of paleontological chimeras:*Brontosaurus*Lametasaurus...
of different animals.
Description and history
Technosaurus is based onHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
TTUP
Texas Tech University
Texas Tech University, often referred to as Texas Tech or TTU, is a public research university in Lubbock, Texas, United States. Established on February 10, 1923, and originally known as Texas Technological College, it is the leading institution of the Texas Tech University System and has the...
P9021, which initially consisted of a premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
(tip of the upper jaw), two lower jaw pieces, a back vertebra, and an astragalus
Talus bone
-External links:* *...
. Technosaurus and its type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, T. smalli, were named by Sankar Chatterjee
Sankar Chatterjee
Sankar Chatterjee is a paleontologist, and is the Paul W. Horn Professor of Geosciences at Texas Tech University and Curator of Paleontology at the Museum of Texas Tech University. He earned his Ph. D. from the University of Calcutta in 1970 and was a Post-doctoral Fellow at the Smithsonian...
in 1984. He described it as a fabrosaurid
Fabrosauridae
The Fabrosauridae was originally proposed by Galton , as a group of basal ornithischian dinosaurs from the Early to Middle Jurassic. However, recent studies indicate the Fabrosaurs are not a natural grouping of dinosaurs, and instead consist of unrelated genera.The proposed "Fabrosaurs" descended...
, a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of small early ornithischians now considered to have been an artificial grouping. Material from the quarry where P9021 was found is disassociated and comes from a variety of Late Triassic animals,
which would prove problematic.
The genus was reviewed in 1991 by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
, who interpreted the premaxilla and a fragment from the front of the lower jaw as pertaining to a hatchling prosauropod, and found the vertebra to be indeterminate and the astragalus an unidentifiable fragment. Thus, he restricted the remains to be considered Technosaurus to the second lower jaw piece, a posterior
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
fragment. It was further reviewed in the light of new remains that spurred reevalutation of purported Triassic dinosaurs, particularly ornithischians named from tooth or jaw material. Irmis et al. (2007) agreed with the removal of the vertebra and astragalus, but found no characteristics that were unambiguously dinosaurian in the skull fragments. They noted similarities to Silesaurus in the jaw fragments Sereno had excluded, and themselves excluded the posterior fragment as actually belonging to the unusual rauisuchia
Rauisuchia
Rauisuchia is a group of predatory and mostly large Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph...
n Shuvosaurus
Shuvosaurus
Shuvosaurus is a genus of beaked reptile from the Late Triassic of Texas. It was described by Sankar Chatterjee in 1993 after it was discovered by his son Shuvo. It was initially interpreted as a Triassic member of the Cretaceous dinosaur family Ornithomimidae...
. These authors would later restate their case, concluding that Technosaurus, defined only by the premaxilla and non-Shuvosaurus lower jaw fragment, was a valid, diagnostic genus, but could not be definitely classified beyond Archosauriformes
Archosauriformes
Archosauriformes is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Late Permian...
incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, and was unlikely to be either an ornithischian or sauropodomorph
Sauropodomorpha
Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs which includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The...
dinosaur.