Thrinaxodon was a 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...

, an ermine-sized (30 cm long) therapsid. Pits on the skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

 suggest that Thrinaxodon may have had whiskers
Vibrissae , or whiskers, are specialized hairs usually employed for tactile sensation. The term may also refer to the thick hairs found inside human nostrils, but these have no sensorial function and only operate as an airborne particulate barrier...

, and by extension a protective covering of fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...

. There are suggestions that it was warm-blooded
The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes...

. Even so, Thrinaxodon still laid eggs, and there were many reptilian features in its skeleton.

Its remains were found on South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 and Antarctica, supporting the notion that the two continents were once joined together. This animal lived during the Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Period (248-245 million years ago).

Its name was taken from Greek θρῖναξ "trident
A trident , also called a trishul or leister or gig, is a three-pronged spear. It is used for spear fishing and was also a military weapon. Tridents are featured widely in mythical, historical and modern culture. The major Hindu god, Shiva the Destroyer and the sea god Poseidon or Neptune are...

, three-pronged fork" and ὀδούϛ ὀδόντ- "tooth", but with a Greek language error: *"Thrinacodon" would have been the grammatically correct form.


Thrinaxodon probably lived in shallow burrows dug into hillsides or riverbanks.

A low-slung, sharp-toothed 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...

, Thrinaxodon lived in burrows, and its well-differentiated teeth suggest it ate small creatures like insects, reptiles, and other small animals. Clues to its remains show that this creature was more mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

-like than its synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...

 ancestors. It had a fairly large head/skull with pits in the bone suggesting it had whiskers which, in turn, hints that its body was hairy. An enlarged dentary bone strengthened either side of the lower jaw and contained sockets for its teeth. Its chest and lower back regions were probably separated by a diaphragm
Thoracic diaphragm
In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

 - a muscular sheet that contracted to fill lungs, and would have enabled Thrinaxodon to breathe more efficiently than its ancestors.

There were many larger predators during the Late Triassic, including some of the earliest carnivorous dinosaurs, such as Coelophysis
Coelophysis , meaning "hollow form" in reference to its hollow bones , is one of the earliest known genera of dinosaur...

. Thrinaxodon had few defenses against these.

In popular culture

  • In the television series Walking with Dinosaurs
    Walking with Dinosaurs
    Walking with Dinosaurs is a six-part documentary television miniseries that was produced by BBC, narrated by Kenneth Branagh, and first aired in the United Kingdom, in 1999. The series was subsequently aired in North America on the Discovery Channel in 2000, with Branagh's voice replaced with that...

    , a scaled-up version of Thrinaxodon was used for the reconstructed 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 seen in the first episode.
  • Thrinaxodon is mentioned in Chapter 16 of Richard Dawkins
    Richard Dawkins
    Clinton Richard Dawkins, FRS, FRSL , known as Richard Dawkins, is a British ethologist, evolutionary biologist and author...

    's The Ancestor's Tale
    The Ancestor's Tale
    The Ancestor's Tale is a 2004 popular science book by Richard Dawkins, with contributions from Dawkins' research assistant Yan Wong. It follows the path of humans backwards through evolutionary history, meeting humanity's cousins as they converge on common ancestors...

  • Thrinaxodon is referenced in Magic: The Gathering
    Magic: The Gathering
    Magic: The Gathering , also known as Magic, is the first collectible trading card game created by mathematics professor Richard Garfield and introduced in 1993 by Wizards of the Coast. Magic continues to thrive, with approximately twelve million players as of 2011...

     through creatures known as Thrinaxes.

  • Thrinaxodon was featured in Episode 5 of Animal Armageddon
    Animal Armageddon
    Animal Armageddon is an American paleontology-based documentary television miniseries that originally aired from to on Animal Planet. All the prehistoric scenes are created 100% in Lightwave...

  • Thrinaxodon was cloned in Ancestor, by Scott Sigler.
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