Palaeosaurus
Encyclopedia
Several very different genera
of prehistoric
animals have been named Palaeosaurus or Paleosaurus since the 1830s. Further confusing the matter, all of the species are poorly known or poorly preserved and both spellings have been used interchangeably, even by the same authors.
The repeated recurrence of this name is most likely due to poor communication between 19th century scientists. Another factor is the name means 'ancient lizard' (Greek
palaios/παλαιος meaning 'ancient' and sauros/σαυρος meaning 'lizard'), which is an appropriate name for any fossil
reptile
.
by French
scientist Isidore Geoffroy Saint-Hilaire
. No species is named, but this genus, found in Germany
, is now considered a junior synonym of the Jurassic
sea-going teleosaurid crocodile Aeolodon.
1836 : Two British
scientists, Henry Riley and Samuel Stutchbury
, briefly and informally publish on two new fossil teeth found in or near the city of Bristol
, England
, which they call Palaeosaurus cylindrodon and P. platyodon. Riley and Stutchbury did not mean to assign these species to Geoffrey Saint-Hilaire's genus; they simply did not know the name had been used. Thecodontosaurus
is also named in this publication.
1840 : German paleontologist Leopold Joseph Fitzinger independently creates the name Palaeosaurus for a third time, describing a fossil reptile skeleton from the Permian
as Palaeosaurus sternbergii. Fitzinger most likely did not know of the original usage either.
1840 : Riley and Stutchbury more fully describe their two species of Palaeosaurus, each based on a single sharp tooth from the Late Triassic Period. The spellings are corrected to read Paleosaurus cylindrodon and Paleosaurus polyodon.
1842 : Sir Richard Owen creates the name Dinosauria. In the same publication, he attempts to redescribe Riley and Stutchbury's Paleosaurus and Thecodontosaurus, which he does not consider to be dinosaurs. Inadvertently, he changes the spelling back to Palaeosaurus, and this spelling is predominantly used from here on. Owen assigns other bones to Palaeosaurus, causing much confusion later, as these bones actually belong to the prosauropod dinosaur Thecodontosaurus.
1847 : Hermann von Meyer recognizes the original 1833 usage of Palaeosaurus and moves P. sternbergii to a new genus, Sphenosaurus
. This animal is very poorly known, but is most likely some sort of primitive reptile.
1870 : Thomas Henry Huxley describes both Thecodontosaurus and Palaeosaurus as dinosaurs for the first time. He considers Palaeosaurus platyodon to be equivalent to Thecodontosaurus antiquus, most likely due to the Thecodontosaurus bones that had been assigned to it by Owen. However, Huxley regards P. cylindrodon as a carnivorous
theropod.
1878 : American
paleontologist Edward Drinker Cope
names the species Palaeosaurus fraserianus for an isolated tooth found in Triassic rocks in Pennsylvania
. Cope's intent is not to establish a new genus but simply a new species within the Palaeosaurus of Riley and Stutchbury. This tooth may be an indeterminate sauropodomorph.
1881 : Yet another species is created, Palaeosaurus stricklandi, for some teeth which probably belong to a phytosaur.
, a German paleontologist, creates the new phytosaur genus Rileya for a humerus
(upper arm bone) and two vertebrae found in the same location as Palaeosaurus cylindrodon, P. platyodon, and Thecodontosaurus antiquus.
1908 : Von Huene recognizes the tooth of Palaeosaurus platyodon as a phytosaur and places it into the genus Rileya, forming the new combination Rileya platyodon.
1908 : In a separate paper, von Huene names Thecodontosaurus subcylindrodon, sometimes called Palaeosaurus subcylindrodon by later authors, which definitely does not belong to Thecodontosaurus and is probably not even a dinosaur. He also describes the prosauropod Sellosaurus and creates the name Teratosaurus minor, for a specimen which later turns out to be a paleontological chimera
, a combination of prosauropod remains and sharp non-dinosaurian teeth.
1914 : Von Huene recognizes that the type species
of Rileya (R. bristolensis) is also a chimera, consisting of two vertebrae from Thecodontosaurus and a phytosaur humerus.
1932 : Von Huene describes numerous prosauropod bones found in Germany. By this time Palaeosaurus cylindrodon has been recognized as a prosauropod because of the prosauropod bones assigned to it by Owen. Von Huene therefore refers his new species to Palaeosaurus, creating the name P. diagnosticus.
1940 : The holotype
tooth of P. cylindrodon is destroyed during World War II
.
1959 : Another German paleontologist, Oskar Kuhn
, finally recognizes that the genus Palaeosaurus created by Riley and Stutchbury in 1836 is preoccupied
and creates the new generic name Palaeosauriscus to contain Palaeosaurus cylindrodon and several of the other species that had been incorrectly assigned to Palaeosaurus.
1961 : Kuhn creates the new name Rileyasuchus
to replace von Huene's Rileya, which is also found to be preoccupied.
1964 : Because of the mistaken association of prosauropod remains with carnivorous teeth, American Edwin Harris Colbert
classifies prosauropods into two groups. Palaeosauria included Palaeosaurus and Teratosaurus, which were thought to be carnivorous. Thecodontosaurus and Plateosaurus
, which had been found with the correct skulls, were included in Plateosauria, which was described as a herbivorous
group.
1973 : Peter Galton
, a British paleontologist, moves the species Palaeosaurus diagnosticus into its own genus, creating the new combination Efraasia diagnostica. For several decades, most scientists consider Efraasia a junior synonym of Sellosaurus, however.
. Most of the skeletal bones ever assigned to Palaeosaurus cylindrodon and P. platyodon are reassigned to Thecodontosaurus. The genera Rileyasuchus and Palaeosauriscus, as well as the species Palaeosaurus cylindrodon and Palaeosaurus platyodon are all declared nomina dubia.
2004 : Adam Yates, another British palaeontologist, redescribes the bones assigned to Sellosaurus. He resurrects the genus Efraasia for some of these bones, to which he assigns the bones that had been described as Teratosaurus minor as well, although not the teeth, which are non-dinosaurian. Like Galton in 1973, Yates' Efraasia also includes the remains previously known as Palaeosaurus diagnosticus, although unlike Galton, Yates calls the species Efraasia minor because von Huene described Teratosaurus minor several pages before Palaeosaurus diagnosticus in his 1908 publication. The name minor therefore takes precedence over diagnostica for this species.
2007 : Peter Galton, reviewing the archosaur
ian fossils of the 1834 Bristol
finds, reaffirms the identification of the two teeth and humeri of Palaeosaurus platyodon (Rileyasuchus) as belonging to a phytosaur, and regards P. cylindrodon (Palaeosauriscus) as an indeterminate archosaur. He concurs that Rileyasuchus is dubious, but suggests that Palaeosauriscus could be valid, based on its now-lost tooth with a "subcircular cross-section and fine, obliquely inclined denticles".
. Richard Owen's mistake of associating prosauropod skeletal remains with the carnivorous teeth which Riley and Stutchbury called Palaeosaurus, combined with von Huene's Teratosaurus minor, which was also a combination of carnivore and prosauropod remains, led paleontologists to view prosauropods as carnivorous animals for quite a long time. This error made it into several textbooks and other dinosaur reference works.
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 prehistoric
Prehistory
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...
animals have been named Palaeosaurus or Paleosaurus since the 1830s. Further confusing the matter, all of the species are poorly known or poorly preserved and both spellings have been used interchangeably, even by the same authors.
The repeated recurrence of this name is most likely due to poor communication between 19th century scientists. Another factor is the name means 'ancient lizard' (Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
palaios/παλαιος meaning 'ancient' and sauros/σαυρος meaning 'lizard'), which is an appropriate name for any fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
.
Species List
- Palaeosaurus (no species named) — a teleosaurid crocodileCrocodiliaCrocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
. May be a junior synonym of Aeolodon. - "Palaeosaurus" cylindrodon — an indeterminate archosaurArchosaurArchosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
- "Palaeosaurus" diagnosticus — a prosauropod dinosaurDinosaurDinosaurs 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...
; synonym of EfraasiaEfraasiaEfraasia is a genus of basal sauropodomorph dinosaur. It was a herbivore which lived during the middle Norian stage of the Late Triassic, around 210 million years ago, in what is now Germany... - "Palaeosaurus" fraserianus — a possible sauropodomorph
- "Palaeosaurus" platyodon — an indeterminate phytosaurPhytosaurPhytosaurs are an extinct group of large semi-aquatic Late Triassic archosaurs. Phytosaurs belong to the family Phytosauridae and the order Phytosauria. They were long-snouted and heavily armoured, bearing a remarkable resemblance to modern crocodiles in size, appearance, and lifestyle, an example...
- "Palaeosaurus" sternbergii — an indeterminate reptile
- "Palaeosaurus" stricklandi — an indeterminate phytosaur
- "Palaeosaurus" subcylindrodon — a possible dinosaurDinosaurDinosaurs 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...
omorph
19th century
1833 : Palaeosaurus is first named as a genusGenus
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...
by French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
scientist Isidore Geoffroy Saint-Hilaire
Isidore Geoffroy Saint-Hilaire
Isidore Geoffroy Saint-Hilaire was a French zoologist and an authority on deviation from normal structure. He coined the term ethology.He was born in Paris, the son of Étienne Geoffroy Saint-Hilaire...
. No species is named, but this genus, found in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, is now considered a junior synonym of the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
sea-going teleosaurid crocodile Aeolodon.
1836 : Two British
United Kingdom of Great Britain and Ireland
The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom during the period when what is now the Republic of Ireland formed a part of it....
scientists, Henry Riley and Samuel Stutchbury
Samuel Stutchbury
-External links:**...
, briefly and informally publish on two new fossil teeth found in or near the city of Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, which they call Palaeosaurus cylindrodon and P. platyodon. Riley and Stutchbury did not mean to assign these species to Geoffrey Saint-Hilaire's genus; they simply did not know the name had been used. Thecodontosaurus
Thecodontosaurus
Thecodontosaurus is a genus of herbivorous basal sauropodomorph dinosaur which lived during the late Triassic period ....
is also named in this publication.
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
as Palaeosaurus sternbergii. Fitzinger most likely did not know of the original usage either.
1840 : Riley and Stutchbury more fully describe their two species of Palaeosaurus, each based on a single sharp tooth from the Late Triassic Period. The spellings are corrected to read Paleosaurus cylindrodon and Paleosaurus polyodon.
1842 : Sir Richard Owen creates the name Dinosauria. In the same publication, he attempts to redescribe Riley and Stutchbury's Paleosaurus and Thecodontosaurus, which he does not consider to be dinosaurs. Inadvertently, he changes the spelling back to Palaeosaurus, and this spelling is predominantly used from here on. Owen assigns other bones to Palaeosaurus, causing much confusion later, as these bones actually belong to the prosauropod dinosaur Thecodontosaurus.
1847 : Hermann von Meyer recognizes the original 1833 usage of Palaeosaurus and moves P. sternbergii to a new genus, Sphenosaurus
Sphenosaurus
Sphenosaurus is a poorly known genus of procolophonid, a type of prehistoric reptile from the Permian. Originally assigned the name Palaeosaurus sternbergii, by...
. This animal is very poorly known, but is most likely some sort of primitive reptile.
1870 : Thomas Henry Huxley describes both Thecodontosaurus and Palaeosaurus as dinosaurs for the first time. He considers Palaeosaurus platyodon to be equivalent to Thecodontosaurus antiquus, most likely due to the Thecodontosaurus bones that had been assigned to it by Owen. However, Huxley regards P. cylindrodon as a carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
theropod.
1878 : American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
paleontologist Edward Drinker Cope
Edward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...
names the species Palaeosaurus fraserianus for an isolated tooth found in Triassic rocks in Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
. Cope's intent is not to establish a new genus but simply a new species within the Palaeosaurus of Riley and Stutchbury. This tooth may be an indeterminate sauropodomorph.
1881 : Yet another species is created, Palaeosaurus stricklandi, for some teeth which probably belong to a phytosaur.
20th century
1902 : Friedrich von HueneFriedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
, a German paleontologist, creates the new phytosaur genus Rileya for a humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
(upper arm bone) and two vertebrae found in the same location as Palaeosaurus cylindrodon, P. platyodon, and Thecodontosaurus antiquus.
1908 : Von Huene recognizes the tooth of Palaeosaurus platyodon as a phytosaur and places it into the genus Rileya, forming the new combination Rileya platyodon.
1908 : In a separate paper, von Huene names Thecodontosaurus subcylindrodon, sometimes called Palaeosaurus subcylindrodon by later authors, which definitely does not belong to Thecodontosaurus and is probably not even a dinosaur. He also describes the prosauropod Sellosaurus and creates the name Teratosaurus minor, for a specimen which later turns out to be a paleontological 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...
, a combination of prosauropod remains and sharp non-dinosaurian teeth.
1914 : Von Huene recognizes that the 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...
of Rileya (R. bristolensis) is also a chimera, consisting of two vertebrae from Thecodontosaurus and a phytosaur humerus.
1932 : Von Huene describes numerous prosauropod bones found in Germany. By this time Palaeosaurus cylindrodon has been recognized as a prosauropod because of the prosauropod bones assigned to it by Owen. Von Huene therefore refers his new species to Palaeosaurus, creating the name P. diagnosticus.
1940 : The holotype
Holotype
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...
tooth of P. cylindrodon is destroyed during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
.
1959 : Another German paleontologist, Oskar Kuhn
Oskar Kuhn
Oskar Kuhn was a German palaeontologist.-Life and career:Kuhn was educated in Dinkelsbühl and Bamberg and then studied natural science, specialising in geology and paleontology, at the University of Munich, from which he received his D. Phil...
, finally recognizes that the genus Palaeosaurus created by Riley and Stutchbury in 1836 is preoccupied
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
and creates the new generic name Palaeosauriscus to contain Palaeosaurus cylindrodon and several of the other species that had been incorrectly assigned to Palaeosaurus.
1961 : Kuhn creates the new name Rileyasuchus
Rileyasuchus
Rileyasuchus is a genus of phytosaur from the Rhaetian of England. It has a confusing history, being associated with the taxonomy of Palaeosaurus and Thecodontosaurus, and being a replacement name for a preoccupied genus Rileyasuchus (meaning "Riley’s crocodile") is a genus of phytosaur from...
to replace von Huene's Rileya, which is also found to be preoccupied.
1964 : Because of the mistaken association of prosauropod remains with carnivorous teeth, American Edwin Harris Colbert
Edwin Harris Colbert
Edwin Harris Colbert was a distinguished American vertebrate paleontologist and prolific researcher and author. He received his A.B. from the University of Nebraska, then his Masters and Ph.D. from Columbia University, finishing in 1935.Born in Clarinda, Iowa, he grew up in Maryville, Missouri...
classifies prosauropods into two groups. Palaeosauria included Palaeosaurus and Teratosaurus, which were thought to be carnivorous. Thecodontosaurus and Plateosaurus
Plateosaurus
Plateosaurus is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 216 to 199 million years ago, in what is now Central and Northern Europe. Plateosaurus is a basal sauropodomorph dinosaur, a so-called "prosauropod"...
, which had been found with the correct skulls, were included in Plateosauria, which was described as a herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
group.
1973 : Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
, a British paleontologist, moves the species Palaeosaurus diagnosticus into its own genus, creating the new combination Efraasia diagnostica. For several decades, most scientists consider Efraasia a junior synonym of Sellosaurus, however.
21st century
2000 : Thecodontosaurus is redescribed by a team of paleontologists led by Michael BentonMichael J. Benton
Michael J. Benton is a British paleontologist, a Fellow of the Royal Society of Edinburgh, and professor of vertebrate palaeontology in the Department of Earth Sciences at the University of Bristol....
. Most of the skeletal bones ever assigned to Palaeosaurus cylindrodon and P. platyodon are reassigned to Thecodontosaurus. The genera Rileyasuchus and Palaeosauriscus, as well as the species Palaeosaurus cylindrodon and Palaeosaurus platyodon are all declared nomina dubia.
2004 : Adam Yates, another British palaeontologist, redescribes the bones assigned to Sellosaurus. He resurrects the genus Efraasia for some of these bones, to which he assigns the bones that had been described as Teratosaurus minor as well, although not the teeth, which are non-dinosaurian. Like Galton in 1973, Yates' Efraasia also includes the remains previously known as Palaeosaurus diagnosticus, although unlike Galton, Yates calls the species Efraasia minor because von Huene described Teratosaurus minor several pages before Palaeosaurus diagnosticus in his 1908 publication. The name minor therefore takes precedence over diagnostica for this species.
2007 : Peter Galton, reviewing the archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
ian fossils of the 1834 Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
finds, reaffirms the identification of the two teeth and humeri of Palaeosaurus platyodon (Rileyasuchus) as belonging to a phytosaur, and regards P. cylindrodon (Palaeosauriscus) as an indeterminate archosaur. He concurs that Rileyasuchus is dubious, but suggests that Palaeosauriscus could be valid, based on its now-lost tooth with a "subcircular cross-section and fine, obliquely inclined denticles".
Effect on paleontology
The confusion surrounding Palaeosaurus extends well beyond nomenclatureBinomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
. Richard Owen's mistake of associating prosauropod skeletal remains with the carnivorous teeth which Riley and Stutchbury called Palaeosaurus, combined with von Huene's Teratosaurus minor, which was also a combination of carnivore and prosauropod remains, led paleontologists to view prosauropods as carnivorous animals for quite a long time. This error made it into several textbooks and other dinosaur reference works.
External links
- The story of Palaeosaurus and Thecodontosaurus from The Bristol Dinosaur Project
- A series of posts to the Dinosaur Mailing List by George Olshevsky, regarding the history of Palaeosaurus: 1 2 3 4