ON TOOTH SUCCESSION IN<i>DIADEMODON</i>

Osborn, J.W.

doi:10.1111/j.1558-5646.1974.tb00733.x

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…Although incomplete, the main cusp of those two teeth appears to be linguomesially oriented and subcircular in outline. The transitional upper postcanines (the intermediate gomphodont of Osborn, 1974) were lost in some specimens of Diademodon such as BSP 1934 VIII 14 in which they probably were replaced by gomphodont postcanines, following the replacement model proposed by Hopson (1971) and Osborn (1974).…”

Section: Resultsmentioning

confidence: 92%

“…Dental morphology: The dental morphology, postcanine microstructure, dental replacement pattern, and postcanine occlusion of D. tetragonus are fairly well-known (Seeley, 1894, 1895, 1908; Watson, 1911, 1913; Broili & Schröder, 1935; Brink, 1955, 1963, 1977; Crompton, 1955, 1963, 1972; Fourie, 1963; Ziegler, 1969; Hopson, 1971; Osborn, 1974; Grine, 1977). Few of these studies provide, however, detailed information and illustrations on the dental morphology and a thorough description of the anatomy of the incisors, canines, and postcanines is here provided.…”

Section: Resultsmentioning

confidence: 99%

“…This paper: (i) proposes a standardized list of terms and abbreviations for incisors, canines, and postcanines anatomical entities, with the goal of facilitating future descriptions and illustrations of the gomphodont dentition; and (ii) provides a comprehensive description and detailed illustrations of the dentition of all known diademodontid and trirachodontid taxa. Tooth replacement pattern and postcanine occlusion, which were treated in detail by several authors for Diademodontidae and Trirachodontidae (Crompton, 1955, 1972; Fourie, 1963; Ziegler, 1969; Hopson, 1971; Osborn, 1974; Sidor & Hopson, 2018), is beyond the scope of this paper. Likewise, a comprehensive description of the dentition of Traversodontidae, which will form the base of another contribution, falls outside the scope of this study.…”

Section: Introductionmentioning

confidence: 99%

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A proposed terminology for the dentition of gomphodont cynodonts and dental morphology in Diademodontidae and Trirachodontidae

Hendrickx

Abdala

Choiniere

2019

PeerJ

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Gomphodont cynodonts were close relatives of mammals and one of the Mesozoic lineages of cynodont therapsids that became extinct at the end of the Triassic. Gomphodonts were omnivorous to herbivorous animals characterized by labiolingually expanded postcanines, which allowed tooth-to-tooth occlusion. The morphology of the upper and lower postcanines presents important means of distinguishing among major lineages within Gomphodontia, that is, Diademodontidae, Trirachodontidae, and Traversodontidae, but the dentition of most Diademodontidae and Trirachodontidae remain poorly documented. Here, we present a comprehensive description of the dentition of each diademodontid and trirachodontid species, as well as detailed illustrations of each dental unit, after firsthand examination of material and 3D reconstructions of postcanine teeth. Based on dental morphology,Trirachodon berryiand “Trirachodon kannemeyeri,” considered as separate taxa by some authors are here interpreted as representing different ontogenetic stages of the same species. Likewise,SinognathusandBeishanodon, thought to belong to non-cynognathian cynodonts and traversodontids by some authors, are referred to Trirachodontidae and Gomphodontia based on dental characters, respectively. Finally, we propose a standardized list of terms and abbreviations for incisors, canines, and postcanines anatomical entities, with the goal of facilitating future descriptions and communication between researchers studying the gomphodont dentition.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A proposed terminology for the dentition of gomphodont cynodonts and dental morphology in Diademodontidae and Trirachodontidae

Hendrickx

Abdala

Choiniere

2019

PeerJ

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“…The relative abundance of Thrinaxodon has indeed also contributed to its detailed study, which includes a large body of literature focusing on the tooth replacement pattern [39][40][41][42][43][44]. Only the Middle Triassic gomphodont cynodont Diademodon has undergone a comparable amount of research on tooth replacement [45][46][47][48][49]. In contrast, only recently has a study reporting tooth replacement of the maxillary canines in a single specimen of Galesaurus been published [50].…”

Section: Remains Of Galesaurus Are Known Exclusively From the Lower Tmentioning

confidence: 99%

Tooth replacement patterns in the Early Triassic epicynodont Galesaurus planiceps (Therapsida, Cynodontia)

et al. 2020

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Sixteen specimens of the Early Triassic cynodont Galesaurus planiceps (including eight that were scanned using micro-computed tomography) representing different ontogenetic stages were assembled to study the dental replacement in the species. The growth series shows that the incisors and postcanines continue to develop and replace, even in the largest (presumably oldest) specimen. In contrast, replacement of the canines ceased with the attainment of skeletal maturity, at a basal skull length of ~90 mm, suggesting that Galesaurus had a finite number of canine replacement cycles. Additionally, the functional canine root morphology of these larger specimens showed a tendency to be open-rooted, a condition not previously reported in Mesozoic theriodonts. An alternating pattern of tooth replacement was documented in the maxillary and mandibular postcanine series. Both postcanine series increased in tooth number as the skull lengthened, with the mandibular postcanine series containing more teeth than the maxillary series. In the maxilla, the first postcanine is consistently the smallest tooth, showing a proportional reduction in size as skull length increased. The longer retention of a tooth in this first locus is a key difference between Galesaurus and Thrinaxodon, in which the mesial-most postcanines are lost after replacement. This difference has contributed to the lengthening of the postcanine series in Galesaurus, as teeth continued to be added to the distal end of the tooth row through ontogeny. Overall, there are considerable differences between Galesaurus and Thrinaxodon relating to the replacement and development of their teeth.

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“…Eruption occurred sequentially from front to back of the tooth row, with the posterior sectorials, when present, being replaced by gomphodont or other sectorial teeth 24,29,31,51 . In the diademodontid Diademodon , at least three generations of postcanines were present at the same time, with distinct morphologies (conical, gomphodont, sectorial), continually replacing each other throughout the animal’s life 29,58 . Trirachodontids, such as Cricodon metabolus , had sectorial and gomphodont postcanines as adults, but juvenile specimens show that an initial generation of cheek teeth was completely sectorial, followed by several waves of replacement 59,60 .…”

Section: Discussionmentioning

confidence: 99%

Early evidence of molariform hypsodonty in a Triassic stem-mammal

et al. 2019

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Hypsodonty, the occurrence of high-crowned teeth, is widespread among mammals with diets rich in abrasive material, such as plants or soil, because it increases the durability of dentitions against wear. Hypsodont postcanine teeth evolved independently in multiple mammalian lineages and in the closely related mammaliaforms since the Jurassic period. Here, we report the oldest record, to our knowledge, of hypsodont postcanines in the non-mammaliaform stem-mammal, Menadon besairiei , from the early Late Triassic. The postcanines are long and columnar, with open roots. They were not replaced in older individuals and remained functional after the total wear of the crown enamel. Dental histology suggests that, convergently to hypsodont mammals, wear was compensated by the prolonged growth of each postcanine, resulting in dentine hypsodont teeth most similar to extant xenarthran mammals. These findings highlight the constraints imposed by limited tooth replacement and tooth wear in the evolutionary trajectories of herbivorous mammals and stem-mammals.

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ON TOOTH SUCCESSION INDIADEMODON

Cited by 11 publications

References 9 publications

A proposed terminology for the dentition of gomphodont cynodonts and dental morphology in Diademodontidae and Trirachodontidae

A proposed terminology for the dentition of gomphodont cynodonts and dental morphology in Diademodontidae and Trirachodontidae

Tooth replacement patterns in the Early Triassic epicynodont Galesaurus planiceps (Therapsida, Cynodontia)

Early evidence of molariform hypsodonty in a Triassic stem-mammal

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