Traversodontidae
Encyclopedia
Traversodontidae is a family
of herbivorous
cynodont
s. Traversodonts were primarily Gondwana
n, with many species known from Africa
and South America
. Recently, traversodonts have also been found from Europe
and eastern North America
. Traversodonts first appeared in the Middle Triassic
, diversified in the Late Triassic
, and became extinct in the Early Jurassic
. The family Traversodontidae was created by Friedrich von Huene
in 1936 for cynodonts first found in São Pedro do Sul
in Paleorrota
, Brazil
.
n cynodonts. As an adaptation toward eating plants, they have wide postcanine teeth behind large canine
s. These postcanines are closely spaced with their crowns touching each other. Each is usually wider than it is long and is covered in several cusps. Because of their complexity, postcanine teeth are the primary means of identifying and distinguishing different species of traversodonts.
Traversodonts have relatively short skulls. The snout is much narrower than the back of the skull. The tip of the snout is wider than the middle, as it constricts behind the large canines. The tooth rows of the upper jaws are inset while the maxillae and zygomatic arch
es extend outward, suggesting that traversodonts may have had cheeks. Primitive features of traversodonts include costal plates around the vertebrae, which stabilize the spine. These plates were lost in more advanced traversodonts like Exaeretodon
.
and Habayia
were very small. These traversodonts lived during the Rhaetian
stage of the latest Triassic when rising sea levels divided western Europe into an island archipelago
. Traversodontids on these islands likely became smaller as a result of insular dwarfism
.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of 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...
cynodont
Cynodont
Cynodontia or cynodonts are a taxon of therapsids which first appeared in the Late Permian and were eventually distributed throughout all seven continents by the Early Triassic . This clade includes modern mammals and their extinct close relatives. They were one of the most diverse groups of...
s. Traversodonts were primarily Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
n, with many species known from Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Recently, traversodonts have also been found from Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and eastern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Traversodonts first appeared in 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...
, diversified in the 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...
, and became extinct in the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
. The family Traversodontidae was created by 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:...
in 1936 for cynodonts first found in São Pedro do Sul
São Pedro do Sul, Rio Grande do Sul
- Paleontology :This city belongs to the geopark of Paleorrota.Museum of the city that have fossils:#Museum Paleontologic and Archaeological Walter Ilha.-Day of Paleorrota:...
in Paleorrota
Paleorrota
Paleorrota , is a geopark located in the center of the Brazilian state of Rio Grande do Sul. The rocks and fossils found along the route date back to the times when there was only one supercontinent Pangaea....
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
.
Description
Traversodonts are members of Gomphodontia, a group of herbivorous cynognathiaCynognathia
The Cynognathians are one of the two major clades of the infraorder Eucynodontia, the other being the Probainognathians. Cynognathus, the most basal representative of the clade was a carnivore, unlike most cynognathians. The cynognathians were mostly mammal-like, but the subgroup Tritylodontids...
n cynodonts. As an adaptation toward eating plants, they have wide postcanine teeth behind large canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
s. These postcanines are closely spaced with their crowns touching each other. Each is usually wider than it is long and is covered in several cusps. Because of their complexity, postcanine teeth are the primary means of identifying and distinguishing different species of traversodonts.
Traversodonts have relatively short skulls. The snout is much narrower than the back of the skull. The tip of the snout is wider than the middle, as it constricts behind the large canines. The tooth rows of the upper jaws are inset while the maxillae and zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es extend outward, suggesting that traversodonts may have had cheeks. Primitive features of traversodonts include costal plates around the vertebrae, which stabilize the spine. These plates were lost in more advanced traversodonts like Exaeretodon
Exaeretodon
Exaeretodon is a genus of traversodontid cynodont; several species are known, from various formations. E. argentinus, E. frenguelli, and E. vincei are from the Carnian-age Ischigualasto Formation of Argentina. E. major and E. riograndensis are from the Ladinian-age portion of the Santa Maria...
.
Paleobiology
While most traversodonts were relatively large cynodonts, some Late Triassic European forms like MaubeugiaMaubeugia
Maubeugia is a genus of traversodontid cynodont from the Late Triassic of France. Isolated postcanine teeth are known from Saint-Nicolas-de-Port in northeastern France. The type species M. lotharingica was named in 1997. Many other cynodont teeth were found alongside those of Maubeugia, including...
and Habayia
Habayia
Habayia is a genus of traversodontid cynodont from the Late Triassic of Belgium. A single postcanine tooth was found in Habay-la-Vieille in southern Belgium. Based on the size of the tooth, Habayia was very small. Habayia lived during the Rhaetian stage of the Late Triassic at a time when western...
were very small. These traversodonts lived during the Rhaetian
Rhaetian
The Rhaetian is in geochronology the latest age of the Triassic period or in chronostratigraphy the uppermost stage of the Triassic system. It lasted from 203.6 ± 1.5 to 199.6 ± 0.6 million years ago...
stage of the latest Triassic when rising sea levels divided western Europe into an island archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
. Traversodontids on these islands likely became smaller as a result of insular dwarfism
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...
.