![Broomistega putterilli](https://upload.wikimedia.org/wikipedia/commons/c/c0/Broomistega_putterilli.jpg)
''Broomistega'' is an extinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
temnospondyl
Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carbo ...
amphibian in the family
Rhinesuchidae
Rhinesuchidae is a family of tetrapods that lived primarily in the Permian period. They belonged to the broad group Temnospondyli, a successful and diverse collection of semiaquatic tetrapods which modern amphibians are probably descended from. ...
. It is known from one species, ''Broomistega putterilli'', which was renamed in 2000 from ''Lydekkerina putterilli'' Broom 1930. Fossils are known from the
Early Triassic
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...
''Lystrosaurus'' Assemblage Zone of the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
in the
Karoo Basin of present-day South Africa, a region that had been an
enclave of
Gondwana. Specimens of ''B. putterilli'' were once thought to represent young individuals of another larger rhinesuchid such as ''
Uranocentrodon'', but the species is now regarded as a
paedomorphic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compare ...
taxon, possessing the features of juvenile rhinesuchids into adulthood.
In 2013, a well-preserved skeleton of ''Broomistega'' was discovered alongside the skeleton of the
cynodont ''
Thrinaxodon
''Thrinaxodon'' is an extinct genus of cynodonts, most commonly regarded by its species ''T. liorhinus'' which lived in what are now South Africa and Antarctica during the Early Triassic. ''Thrinaxodon'' lived just after the Permian–Triassic m ...
'' (a mammal relative) in a
cast
Cast may refer to:
Music
* Cast (band), an English alternative rock band
* Cast (Mexican band), a progressive Mexican rock band
* The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis
* ''Cast'', a 2012 album by Trespassers William
...
of a burrow. The individual probably entered the burrow while the cynodont was in a state of
aestivation (dormancy), and afterwards a
flash flood filled the burrow with sediment to preserve both bodies together.
Paleobiology
''Broomistega'' is the only
rhinesuchid known from the
Triassic Period
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
. Its presence in the Early Triassic indicates that rhinesuchids survived the
Permo-Triassic Mass Extinction about 252 million years ago. However, compared to the diversity of rhinesuchids that existed in the
Permian Period
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
, ''Broomistega'' is a very rare component of the Early Triassic
Karoo fauna. It may have been the last surviving representative of the group, making it a relict taxon.
Association with ''Thrinaxodon''
![Odd couple](https://upload.wikimedia.org/wikipedia/commons/5/52/Odd_couple.png)
The most complete skeleton of ''Broomistega'', specimen BP/1/7200, was discovered in the sandstone cast of a burrow (BP/1/5558) after the cast was scanned at the
European Synchrotron Radiation Facility
The European Synchrotron Radiation Facility (ESRF) is a joint research facility situated in Grenoble, France, supported by 22 countries (13 member countries: France, Germany, Italy, the UK, Spain, Switzerland, Belgium, the Netherlands, Denmark, ...
in 2013. The cast was first found in the
Karoo Basin of South Africa by paleontologist
James Kitching
James William Kitching (6 February 1922 – 24 December 2003) was a South African vertebrate palaeontologist and regarded as one of the world’s greatest fossil finders.
Career
His work in the southern hemisphere, including Antarctica, led ...
in 1975, but was left unprepared for many years. Part of a skull of a cynodont was exposed on the surface of the cast, allowing Kitching to attribute it to the genus ''
Thrinaxodon
''Thrinaxodon'' is an extinct genus of cynodonts, most commonly regarded by its species ''T. liorhinus'' which lived in what are now South Africa and Antarctica during the Early Triassic. ''Thrinaxodon'' lived just after the Permian–Triassic m ...
''. Only after the synchrotron scanning was the ''Broomistega'' skeleton found. All bones are preserved except for a few
phalanges of the right hind foot, and nearly all of the bones are
articulated
An articulated vehicle is a vehicle which has a permanent or semi-permanent pivot joint in its construction, allowing it to turn more sharply. There are many kinds, from heavy equipment to buses, trams and trains. Steam locomotives were sometim ...
as they were in life. The skeletons do not show evidence of stiffening due to
rigor mortis
Rigor mortis (Latin: ''rigor'' "stiffness", and ''mortis'' "of death"), or postmortem rigidity, is the third stage of death. It is one of the recognizable signs of death, characterized by stiffening of the limbs of the corpse caused by chemic ...
after death, but are pressed against the sides of the burrow as the animals would have been when alive. The skeleton of BP/1/7200 is preserved belly-up, resting on the right side of the ''Thrinaxodon'' skeleton. This position was probably the result of the individual being pushed on top of the ''Thrinaxodon'' by floodwater entering the burrow.
[
''Broomistega'' is not thought to have been a burrowing animal and was instead ]semiaquatic
In biology, semiaquatic can refer to various types of animals that spend part of their time in water, or plants that naturally grow partially submerged in water. Examples are given below.
Semiaquatic animals
Semi aquatic animals include:
* Ve ...
. The ''Thrinaxodon'' individual preserved in BP/1/5558 was probably the original occupant of the burrow, and the ''Broomistega'' individual probably entered the burrow later. The joints of BP/1/7200 are not well developed, indicating that the individual was a juvenile with large amounts of cartilage in its skeleton. Several ribs on the right side of the skeleton are broken, indicating that the individual was severely injured before entering the burrow, probably by being crushed. The animal was still alive when it entered the burrow because the rib fractures show evidence of healing, but the injury probably impacted its ability to breathe and to move about. Two holes are present on the skull roof of BP/1/7200. Although they resemble bite marks, they do not match with the teeth of the ''Thrinaxodon'' specimen.[
The presence of two different species of large vertebrates in the same burrow is unusual. Modern examples of this association are usually the result of predator-prey interactions (for example, a predator storing the body of its prey in the burrow) or mutualistic relationships whereby the original occupant gains protection from predators by the presence of the second inhabitant. However, the benefit of cohabitation usually only works when there are multiple burrows, casting doubt on the possibility that the ''Thrinaxodon'' was benefiting from the presence of the ''Broomistega''. Because the ''Broomistega'' skeleton lacks any sign of damage caused by the ''Thrinaxodon'', the two were probably not predator and prey. The most likely explanation for the association as of 2013 is that the ''Thrinaxodon'' tolerated the ''Broomistega'' or was unable to remove it, possibly because it was aestivating. As is the case with many modern amphibians, the ''Broomistega'' probably entered the burrow to seek temporary shelter. During the Early Triassic the Karoo Basin was seasonally arid, so the ''Thrinaxodon'' may have been aestivating to conserve energy during a time when resource availability was low and the normally aquatic ''Broomistega'' may have entered to burrow to escape the hot and dry conditions of its environment.][
]
References
{{Taxonbar, from=Q4975338
Triassic temnospondyls of Africa
Articles containing video clips
Early Triassic amphibians of Africa
Fossil taxa described in 2000