Ctenosauriscus
Encyclopedia
Ctenosauriscus is an extinct genus
of sail
-backed poposauroid
archosaur
from Early Triassic
deposits of Lower Saxony
in northern Germany
. It gives its name to the family Ctenosauriscidae
, which includes other sail-backed poposauroids such as Arizonasaurus
. Fossils have been found in latest Olenekian
deposits around 247.5-247.2 million years old, making it one of the first known archosaurs.
The most prominent feature of Ctenosauriscus is its sail-like back, formed from elongated neural spines of the dorsal and cervical vertebrae. These spines curve slightly forward at the front of the sail and slightly backward at the back of the sail. Although other poposauroids like Lotosaurus
and the ctenosauriscids Hypselorhachis
and Xilousuchus
also have elongated spines, the sail of Ctenosauriscus is one of the largest in the group. Among ctenosauriscids, Ctenosauriscus is most similar to Arizonasaurus
from the Middle Triassic
of the southwestern United States
. Both of these ctenosauriscids have elongated vertebrae spines up to 12 times the height of the bodies of the vertebrae. The ends of the spines are wider in Ctenosauriscus, and Ctenosauriscus also has larger projections on the centra
of the dorsal vertebrae. Hypselorhachis also has neural spines that are widened at the end, but they are shorter than those of Ctenosauriscus. Lotosaurus from the Middle Triassic of China
also has elongate spines, but they are straighter, broader, and much shorter than those of Ctenosauriscus.
, GZG.V.4191, a single partial preserved postcrania
l skeleton
including partial vertebral column
, rib
s and girdle
. The holotype is composed of four slabs, which were labeled A1, A2, B1, and B2 in a 2011 study. Slabs A1 and B1 form the part and slabs A2 and B2 form the counterpart. The holotype was discovered in early 1871 in the Bremke dell locality, near the county of Göttingen
. The holotype was found in a deposit called the Solling-Bausandstein, which is an outcropping of the upper Middle Buntsandstein
in the region of Eichsfeld
. After the holotype was uncovered, it was housed in the University of Göttingen . It remained undescribed until 1902, when German paleontologist Friedrich von Huene
designated it to the new species Ctenosaurus koeneni.
Von Huene considered C. koeneni to be a late-surviving species of Pelycosauria, a group of distant mammal relatives otherwise known only from the Late Carboniferous and Early Permian. He based this classification on its similarity with sail-backed pelycosaurs like Dimetrodon
. Austrian paleontologist Othenio Abel placed C. koeneni as a temnospondyl amphibian closely related to the sail-backed Platyhystrix
(which, like Dimetrodon, was from the Early Permian). The name Ctenosaurus was preoccupied by a species of iguanid lizard (now called Ctenosaura
), so a new generic name, Ctenosauriscus, was erected by paleontologist Oskar Kuhn
in 1964. Paleontologist B. Krebs redescribed the holotype and reclassified Ctenosauriscus as an archosaur based on similarities with the sail-backed pseudosuchian Hypselorhachis
from the Middle Triassic
Manda Beds of Tanzania
.
Ctenosauriscus was found in the Solling Formation, which was deposited about 247.5 to 247.2 million years ago in the latest Olenekian stage. This age is based on radiometric dating
and records of Milankovitch cycles
in the formation. Ctenosauriscus was traditionally thought to have lived during the Middle Triassic
after Krebs placed the Middle Buntsandstein within the Anisian
stage.
A redescription of the holotype was published by Richard J. Butler, Stephen L. Brusatte, Mike Reich, Sterling J. Nesbitt, Rainer R. Schoch and Jahn J. Hornung in 2011. They did not identify any autapomorphies for Ctenosauriscus, but they noted that the holotype can be distinguished from other ctenosauriscids by a unique combination of characters. Ctenosauriscus is one of the oldest archosaur
s to date, alongside with Vytshegdosuchus
from Russia
and probably Xilousuchus, a ctenosauriscid from China.
vertebrae, not the dorsal vertebrae. The sail of Ctenosauriscus would also have shifted its center of weight toward the front of the body, making bipedal locomotion difficult or impossible.
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 sail
Sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...
-backed poposauroid
Poposauroidea
Poposauroidea is a clade of rauisuchians. It includes poposaurids, shuvosaurids, and ctenosauriscids, but excludes the large predatory quadrupedal rauisuchians such as rauisuchids and prestosuchids. Although it was first formally defined in 2007, the term has been used for many years...
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...
from Early Triassic
Early Triassic
The Early Triassic is the first of three epochs of the Triassic period of the geologic timescale. It spans the time between 251 ± 0.4 Ma and 245 ± 1.5 Ma . Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy...
deposits of Lower Saxony
Lower Saxony
Lower Saxony is a German state situated in north-western Germany and is second in area and fourth in population among the sixteen states of Germany...
in northern 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...
. It gives its name to the family Ctenosauriscidae
Ctenosauriscidae
Ctenosauriscidae is an extinct family of pseudosuchian archosaurs within the clade Poposauroidea. Ctenosauriscids existed in Africa, Asia, Europe and North America during the Early Triassic to the Middle Triassic period . All species had large "sails" on their backs...
, which includes other sail-backed poposauroids such as Arizonasaurus
Arizonasaurus
Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic . Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongate neural spines of the...
. Fossils have been found in latest Olenekian
Olenekian
In the geologic timescale, the Olenekian is an age in the Early Triassic epoch or a stage in the Lower Triassic series. It spans the time between 249.7 ± 0.7 Ma and 245 ± 0.7 Ma . The Olenekian follows the Induan and is followed by the Anisian.The Olenekian saw the deposition of a large part of the...
deposits around 247.5-247.2 million years old, making it one of the first known archosaurs.
Description
Lotosaurus
Lotosaurus is an is an extinct genus of sail-backed poposauroid known from Hunan Province of central China.-Description:Lotosaurus is known from the holotype IVPP V 4881 , articulated well-preserved skeleton, and from the referred specimens IVPP V 48013, skull, articulated and...
and the ctenosauriscids Hypselorhachis
Hypselorhachis
Hypselorhachis is a genus of extinct reptile, possibly a ctenosauriscid archosaur related to Ctenosauriscus. It lived during the Triassic Period. It is currently known only from a single vertebra found from the Middle Triassic Manda Beds in Tanzania....
and Xilousuchus
Xilousuchus
Xilousuchus is an extinct genus of poposauroid from lower Triassic deposits of Fugu County of northeastern Shanxi Province, China. It is known from the holotype, IVPP V 6026, a single well-preserved partial skeleton including the skull. It was found from the Heshanggou Formation of the...
also have elongated spines, the sail of Ctenosauriscus is one of the largest in the group. Among ctenosauriscids, Ctenosauriscus is most similar to Arizonasaurus
Arizonasaurus
Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic . Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongate neural spines of the...
from the Middle Triassic
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
of the southwestern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Both of these ctenosauriscids have elongated vertebrae spines up to 12 times the height of the bodies of the vertebrae. The ends of the spines are wider in Ctenosauriscus, and Ctenosauriscus also has larger projections on the centra
Body of vertebra
The body is the largest part of a vertebra, and is more or less cylindrical in shape. For vertebrates other than humans, this structure is usually called a centrum....
of the dorsal vertebrae. Hypselorhachis also has neural spines that are widened at the end, but they are shorter than those of Ctenosauriscus. Lotosaurus from the Middle Triassic of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
also has elongate spines, but they are straighter, broader, and much shorter than those of Ctenosauriscus.
History
Ctenosauriscus is known from the holotypeHolotype
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...
, GZG.V.4191, a single partial preserved postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
including partial vertebral column
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
, rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
s and girdle
Girdle
A girdle is a garment that encircles the lower torso, perhaps extending below the hips, and worn often for support. The word girdle originally meant a belt. In modern English, the term girdle is most commonly used for a form of women's foundation wear that replaced the corset in popularity...
. The holotype is composed of four slabs, which were labeled A1, A2, B1, and B2 in a 2011 study. Slabs A1 and B1 form the part and slabs A2 and B2 form the counterpart. The holotype was discovered in early 1871 in the Bremke dell locality, near the county of Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...
. The holotype was found in a deposit called the Solling-Bausandstein, which is an outcropping of the upper Middle Buntsandstein
Buntsandstein
The Buntsandstein or Bunter sandstone is a lithostratigraphic and allostratigraphic unit in the subsurface of large parts of west and central Europe...
in the region of Eichsfeld
Eichsfeld
The Eichsfeld is a historical region in the southeast of Lower Saxony and northwest of Thuringia in the south of the Harz mountains...
. After the holotype was uncovered, it was housed in the University of Göttingen . It remained undescribed until 1902, when German paleontologist Friedrich von Huene
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
designated it to the new species Ctenosaurus koeneni.
Dimetrodon
Dimetrodon was a predatory synapsid genus that flourished during the Permian period, living between 280–265 million years ago ....
. Austrian paleontologist Othenio Abel placed C. koeneni as a temnospondyl amphibian closely related to the sail-backed Platyhystrix
Platyhystrix
Platyhystrix was a temnospondyl amphibian with a distinctive sail along its back, similar to the unrelated synapsids, Dimetrodon and Edaphosaurus...
(which, like Dimetrodon, was from the Early Permian). The name Ctenosaurus was preoccupied by a species of iguanid lizard (now called Ctenosaura
Ctenosaura
Ctenosaura is a genus of lizard commonly known as spinytail iguanas. The genus is part of the large lizard family, Iguanidae and is native to Mexico and Central America. The species range in size from about 5 inches to well over one meter. The distinctive feature of this genus is presence of the...
), so a new generic name, Ctenosauriscus, was erected by 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...
in 1964. Paleontologist B. Krebs redescribed the holotype and reclassified Ctenosauriscus as an archosaur based on similarities with the sail-backed pseudosuchian Hypselorhachis
Hypselorhachis
Hypselorhachis is a genus of extinct reptile, possibly a ctenosauriscid archosaur related to Ctenosauriscus. It lived during the Triassic Period. It is currently known only from a single vertebra found from the Middle Triassic Manda Beds in Tanzania....
from the Middle Triassic
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
Manda Beds of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
.
Ctenosauriscus was found in the Solling Formation, which was deposited about 247.5 to 247.2 million years ago in the latest Olenekian stage. This age is based on radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
and records of Milankovitch cycles
Milankovitch cycles
Milankovitch theory describes the collective effects of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković, who worked on it during First World War internment...
in the formation. Ctenosauriscus was traditionally thought to have lived during the Middle Triassic
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
after Krebs placed the Middle Buntsandstein within the Anisian
Anisian
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from 245 million years ago until 237 million years ago, approximately...
stage.
A redescription of the holotype was published by Richard J. Butler, Stephen L. Brusatte, Mike Reich, Sterling J. Nesbitt, Rainer R. Schoch and Jahn J. Hornung in 2011. They did not identify any autapomorphies for Ctenosauriscus, but they noted that the holotype can be distinguished from other ctenosauriscids by a unique combination of characters. Ctenosauriscus is one of the oldest 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...
s to date, alongside with Vytshegdosuchus
Vytshegdosuchus
Vytshegdosuchus is a genus of rauisuchid archosaur. It is known from fossil bones discovered from three localities along the Vychegda River in the Komi Republic of the European section of Russia. These fossils were found in rocks of the upper Yarenskian Gorizont, dating to the late Olenekian stage...
from Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
and probably Xilousuchus, a ctenosauriscid from China.
Paleobiology
A 1998 study proposed that Ctenosauriscus was bipedal and that its elongated neural spines served to absorb the forces exerted from walking on two legs. Although limb bones are unknown, the study found that forces on the tips of the spines were focused on a point below the spinal column, hypothesized to be the knee joint. In the 2011 redescription of Ctenosauriscus, the authors rejected this idea because for forces on the spine to meet at the knee joint, muscles would have to form a direct connection between the knee and the back. Forces exerted from movement travel from the hind legs to the hip and sacralSacral
Sacral may refer to:*sacred*sacrum...
vertebrae, not the dorsal vertebrae. The sail of Ctenosauriscus would also have shifted its center of weight toward the front of the body, making bipedal locomotion difficult or impossible.