''Odontocyclops'' (Greek: “tooth” Greek: “round eye”, a kind of Greek mythological giant with one eye in the midline; "toothy cyclops") is an extinct genus of

Dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, t ...

s that lived in the

Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

. Dicynodonts are believed to be the first major assemblage of terrestrial herbivores.Angielczyk, K. D. 2002. Redescription, phylogenetic position, and stratigraphic significance of the dicynodont genus Odontocyclops (Synap-sida: Anomodontia). Journal of Paleontology 76:1047–1059. Fossils of ''Odontocyclops'' have been found in the

Karoo Basin The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a per ...

of South Africa and the Luangwa Valley of Zambia. The phylogenetic classification of ''Odontocyclops'' has been long under debate, but most current research places them as their own genus of Dicynodonts and being very closely related to ''Rhachiocephalus'' and ''Oudenodon''.

Discovery and classification

The first skull of what would later be named, ''Odontocyclops'', was discovered in 1913 by Rev. J.H White in the Karoo Basin of South Africa. In 1938, additional ''Odontocyclops'' specimens were discovered in the Luangwa Valley of Zambia. Using these specimens and a few later collected skulls Cruickshank and Keyser in their 1979 paper erected a new genus of Dicynodonts to accommodate ''Odontocyclops''.Keyser, A. W., and A. R. I. Cruickshank. 1979. The origins and classification of Triassic Dicynodonts. Transactions of the Geological Society of South Africa, 12:1-35. However, Culver and King did not believe that the diagnostic features listed by Cruickshank and Keyser (1979) distinguished ''Odontocyclops'' from the genus ''Dicynodon''. This later lead King to classify ''Odontocylops'', not as its own genus, but as a synonym for '' Dicynodon''. However, the most current research by Angielczyk has used cladistic data and provided the most current suggested hypothesis that ''Odontocyclops'' represents its own genus of Dicynodont and is very closely related to ''Rhachiocephalus'' and

Oudenodon ''Oudenodon'' is an extinct genus of dicynodont. It was common throughout southern Africa during the Late Permian. Several species of ''Oudenodon'' are known. Both ''O. bainii'', the type species, and ''O. grandis'' are known from South Africa ...

Description

''Odontocyclops'' is distinguished from other dicynodonts by two autapomorphies: elongated nasal bosses and concave dorsal surface of the snout. ''Odontocyclops'' also possesses wide exposure of the parietals on the intertemporal skull roof, the presence of a postcaniniform crest, the absence of a labial fossa, and the presence of a dorsal process on the anterior ramus of the epipterygoid footplate.

Skull

The skull of ''Odontocyclops'' are large compared to other dicynodonts, measuring 60 cm and greater. Large canine tusks are found in some of the specimens, but not others. However, the presence of tusks appears to be variable and not correlated with size. Consequently, it is reasoned that the presence of tusks is not a sexual dimorphism for this genus. The overall shape of the skull is very similar to that of ''Rhachiocepalus''. In dorsal view the snout is notably concave and is formed by large nasal bosses that project medially over the snout. The bone that forms these nasal bosses is covered with numerous fine pits, suggesting the presence of a

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...

covering. Additionally, all known specimens lack premaxillary teeth. This combined with other evidence points towards ''Odontocyclops'' possessing a keratinous beak. Lastly, the

vomer The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms ...

s of ''Odontocyclops'' are fused and they do possess a

secondary palate The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates. In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves med ...

that is relatively flat compared to other dicynodonts and contains low walls. The jaws of the available specimen for examination are poorly preserved. The jaw that has been examined for ''Odontocyclops'', only has preservation of the anterior portion of the jaw. From this available information it was determined that ''Odontocyclops'' lack denary teeth, but do contain a lateral dentary shelf. The presence of the lateral dentary shelf combined with the quadrates being similar in morphology to other dicynodonts suggest that ''Odontocyclops'' used a propalinal sliding feeding mechanism. Its skull clearly had two normal eyes, but the wide open

pineal foramen A parietal eye (third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland, which regulates circadian rhythmicity and hormone production ...

shows that it also had a " pineal eye". In reptiles, the pineal organ senses changes in temperature and light.

Postcranial skeleton

There is only a single left

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

available for examination of ''Odontocyclops''. This humerus possesses largely expanded proximal and distal ends, which are separated by a short shaft. The proximal and distal ends of the humerus are offset by 40 degrees. The proximal portion of the humerus is relatively flat, whereas, the distal potion is convex. The peak of this convexity is at the distal end of the humeral head. Only one left

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

was available for examination of ''Odontocyclops''. This scapula is similar to the scapula of other dicynodonts and consists of a long, curved, spatulate, dorsally expanded blade that arises from a robust, rounded base. The medial surface of the ''Odontocyclops'' scapula blade is relatively smooth and slightly concave. From this specimen there is no evidence that ''Odontocyclops'' had a

cleithrum The cleithrum (: cleithra) is a membrane bone which first appears as part of the skeleton in primitive Osteichthyes, bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key (lock)", by analogy ...

. Additionally, the scapula and coracoid remain separate and are not fused. This lack of fusion is a feature that is seen in other dicynodonts.

Palaeobiology

Diet

Dicynodonts are considered to be the first successful terrestrial herbivores.King, G. (1993). Species longevity and generic diversity in dicynodont mammal-like reptiles. Palaeogeography, Palaeoclimatology, Palaeoecology, 102(3), 321-332. The ''Odontocyclops'' diet most likely consisted of a variety of seeds, leaves, stems, and fleshy parts of plants. It is likely that they possessed a feeding behavior similar to one of their closest relatives, ''Oudenodon'', which had a more upright stance and moved rather slowly. They most likely possessed a browsing feeding behavior, eating vegetation that was 20–100 cm above the ground. (Order No. MQ54209). Available from ProQuest Dissertations & Theses Global. (304663112). Their propalinal sliding mechanism of feeding combined with their sharp keratin beak provided a sharp surface to efficiently cut and grind plant material.

Growth

There exists little information of the specific growth patterns of ''Odontocyclops''. However, by examining general dicynodont growth patterns, an understanding of a similar patterns can be inferred for ''Odontocyclops''. Dicynodonts are characterized by a predominance of fibrolamellar bone tissue in the cortex. Fibroamellar bone is associated with rapid

osteogenesis Osteoblasts (from the Greek language, Greek combining forms for "bone", ὀστέο-, ''osteo-'' and βλαστάνω, ''blastanō'' "germinate") are cell (biology), cells with a single Cell nucleus, nucleus that synthesize bone. However, in the p ...

, therefore, it is suggested that dicynodonts exhibited fast bone growth.Chinsamy-Turan, A. (2012). Forerunners of Mammals : Radiation, Histology, Biology (Life of the past). Bloomington: Indiana University Press. Another pattern of growth in some dicynodonts, including the closest relatives of ''Odontocyclops'', is rapid growth as a juvenile followed by a decrease in growth rate with age. Once again, the available specimen sample size is too small to make definite conclusions about growth patterns of ''Odontocyclops''. However, one of the specimens presumed to be a juvenile is lacking large nasal bosses, suggesting that this is a feature obtained later in life.

Palaeoenvironment

''Odontocyclops'' specimens have been found both in the Karoo Basin of South Africa and the Madumabisa Mudstone of the Luangwa Valley of Zambia. The Karoo Basin was originally formed in the

Late Carboniferous Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * Late (The 77s album), ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudo ...

resulting from the collision of the paleo-Pacific plate with the

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

n plate. The Karoo Basin and Luangwa Valley have yielded a large number of dicynodonts. Their ancient ecosystems occupied a region of low-lying flood plains cut by a series of extensive braided river channels. The Madumabisa Mudstone, within which, ''Odontocyclops'' was found is a formation that is 700 meters thick. It is believed to be formed from sediment deposits of massive mudrock, deposited from sediment rich rivers entering a lake. The Madumabisa Mudstone is a grey/greenish color, but other colors ranging from brownish grey to dark green and red are present.Nyambe, I.A., Dixon, O., 2000. Sedimentology of the Madumabisa Mudstone Formation (Late Permian), Lower Karoo Group, mid-Zambezi Valley Basin, southern Zambia. Journal of African Earth Sciences 30, 535e553.

References

External links

The main groups of non-mammalian synapsids at Mikko's Phylogeny Archive
{{Taxonbar, from=Q9051753 Bidentalia Lopingian synapsids of Africa Fossils of South Africa Fossils of Zambia Fossil taxa described in 1979