Tumor Found in 255 Million Year old Gorgonopsid Tooth Fossil

When paleontologists at the University of Washington cut into the fossilized jaw of a distant mammal relative, they got more than they bargained for -- more teeth, to be specific.

As they report in a letter published Dec. 8 in the Journal of the American Medical Association Oncology, the team discovered evidence that the extinct species harbored a benign tumor made up of miniature, tooth-like structures. Known as a compound odontoma, this type of tumor is common to mammals today. But this animal lived 255 million years ago, before mammals even existed.

"We think this is by far the oldest known instance of a compound odontoma," said senior author Christian Sidor, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture. "It would indicate that this is an ancient type of tumor."

Before this discovery, the earliest known evidence of odontomas came from Ice Age-era fossils.

"Until now, the earliest known occurrence of this tumor was about one million years ago, in fossil mammals," said Judy Skog, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "These researchers have found an example in the ancestors of mammals that lived 255 million years ago. The discovery suggests that the suspected cause of an odontoma isn't tied solely to traits in modern species, as had been thought."

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Were Gorgonopsid Sabre Teeth for Mating Display Purposes?!

Hollywood celebrities spend large amounts of dollars on it. The hunky stud at the local pub thinks he knows it. But the age-old secret has been carefully kept for millions of years. Yet, it seemed obvious to pre-mammalian reptiles that went so far as to evolve mouths full of beautifully crafted teeth. It's your beautifully bleached smile that makes you sexy!

Mammals, like us, have a set of dentition that are neatly divided into three distinct types of teeth -- the incisors at the front of your mouth, the molars in your cheeks, and the canines, that Dracula-type teeth that separates the molars from the incisors. The origin of this separation can be traced back to 300 million years ago, when our ancestors still looked like sprawling reptiles, the pre-mammalian therapsids.

These creatures, like the gorgonopsians (a group of therapsids), had long, sometimes sabre-like canines that was often interpreted as a deadly hunting device. However, there was a problem. Some herbivorous species that only grazed on plants, like the dicynodonts (herbivorous animals, varying in sizes from a rat to an ox, and like warthogs, had two tusks, that gave them their name, which means "two dog tooth").

So, if not for hunting, what were these impressive sets of pointy teeth for? Defence against predators? Nope! These prehistoric characters used them to seduce the beauties!

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The rebuttal to this would be immediately after the gorgons went extinct, a therocephalian genus went through rapid convergent evolution to develop its own sabre teeth implying there was an empty ecological niche.

Eriphostoma microdon: new Specimens of the Oldest Permian Gorgonopsid Found

New information on the morphology and stratigraphic range of the mid-Permian gorgonopsian Eriphostoma microdon Broom, 1911

Authors:

Kammerer et al

Abstract:

New specimens of the oldest gorgonopsian taxon Eriphostoma microdon from the Pristerognathus Assemblage Zone (AZ) of South Africa significantly improve our understanding of the anatomy of this taxon. The new specimens consist of nearly complete skulls and lower jaws and allow for a more complete diagnosis of Eriphostoma than was possible based on the poorly preserved holotype. In addition to the characteristic palatal dentition and delta-shaped palatine bosses previously recognized for Eriphostoma, this taxon can be diagnosed by the presence of three close-packed upper postcanines occupying an indented margin of the maxilla, a large, tetragonal-to-rounded preparietal bone, and large, paired interorbital depressions expanding outwards in front of the pineal boss. The revised diagnosis permits Eoarctops vanderbyli, Galesuchus gracilis, and Scylacognathus parvus to be synonymized with Eriphostoma microdon, as previously suspected. Among gorgonopsians, Eriphostoma is most similar to Aelurosaurus and Gorgonops, although these similarities are likely plesiomorphic for Gorgonopsia. Eriphostoma ranges from the Tapinocephalus AZ (where it is the only valid gorgonopsian known from the Karoo Basin) through the Pristerognathus AZ (where it co-occurs with Gorgonops).

Gorgonopsia Revision Begun With Reexamination of Arctognathus curvimola

Cranial osteology of Arctognathus curvimola, a short-snouted gorgonopsian from the Late Permian of South Africa

Author:

Kammerer

Abstract:

Gorgonopsia is one of the major clades of nonmammalian therapsids and includes the dominant vertebrate predators of the Late Permian. Unfortunately, gorgonopsian taxonomy is extremely problematic, due in large part to the lack of thorough descriptions and clear differential diagnoses for most nominal species. Here, the South African gorgonopsian species Arctognathus curvimola is redescribed based on a well-preserved skull. Autapomorphies identified for A. curvimola include a characteristic curvature to the alveolar margin of the snout, extremely reduced lacrimal, lengthy upper postcanine tooth row and a unique vomerine morphology. The nominal gorgonopsian species Arctognathoides breviceps and Lycaenodontoides bathyrhinus are considered junior synonyms of A. curvimola. Other referred species of Arctognathus (A. whaitsi, A.? cookei and A.? nasuta) share no unique characters with A. curvimola and are removed from the genus; their generic placement is uncertain at present. Previous reports of Arctognathus from Tanzania and the Middle Permian of South Africa are not referable to this taxon. At present, definitive specimens of A. curvimola are restricted to the Upper Permian Cistecephalus and Dicynodon assemblage zones of South Africa.

Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa

Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa

Authors:

1. Nicholas Fordyce (a)
2. Roger Smith (b)
3. Anusuya Chinsamy (a)

Affiliations:

a. Department of Zoology, University of Cape Town, Cape Town, South Africa
b. Iziko South African Museum, Cape Town, South Africa

Abstract:

Dicynodonts are an extinct group of herbivorous non-mammalian therapsids (‘mammal-like’ reptiles) that are widely known from terrestrial Permo-Triassic strata throughout Pangaea. Dicynodont fossil remains are common within the Late Permian Beaufort Group of the Karoo Basin in South Africa. A large, partially articulated dicynodont skeleton recovered from the Tropidostoma Assemblage Zone is taphonomically important in having an unusual disarticulation pattern, bone surface punctures and a broken tooth of an unidentified carnivore associated with it. Here we report on the nature of the bone damage, and the identity of the carnivore that lost a canine tooth whilst scavenging the dicynodont carcass. The morphological characteristics of the serrations on the unidentified tooth were compared with those of contemporaneous carnivores, the gorgonopsians and therocephalians. Scanning electron microscopy analysis of a silicone cast of the unidentified tooth revealed distinctive 0.5-mm square-shaped serrations. Our comparative assessment of the tooth size, curvature, cross-sectional shape and morphology of the serrations revealed that the unidentified canine most closely matched Aelurognathus, a gorgonopsian known from the same assemblage zone.

Gorgons going hyena here.  Kewl!

The paper is open access, btw.