Morphology and function of the palatal dentition in Choristodera

Matsumoto, Ryoko; Evans, SE

doi:10.1111/joa.12414

Cited by 10 publications

(23 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…No premaxillary teeth are completely preserved in CMN 8920, but plicidentine infolding is seen internally near the base of the fragmentary premaxillary teeth. Overall, the marginal teeth show a trend of decreasing size posteriorly (6 mm at 21st alveoli, 2 mm at 47th alveoli), a trend that is consistent with previous descriptions of Champsosaurus and other neochoristoderes (Matsumoto & Evans, 2016).…”

Section: Dentitionsupporting

confidence: 90%

“…This trough is shallow in CMN 8920 compared with those of other Champsosaurus specimens (e.g. TMP 87.36.41, TMP 94.163.01, TMP 86.12.11, CMN 8919; Matsumoto & Evans, ), likely due to crushing of the palatal region.…”

Section: Resultsmentioning

confidence: 74%

“…14). Previous descriptions of Champsosaurus (Matsumoto & Evans, 2016) reported the marginal teeth as having plicidentine, with visible longitudinal striations in the enamel. These striations are not apparent on the maxillary teeth of CMN 8920, but the CT data show internal plicidentine infolding.…”

Section: Dentitionmentioning

confidence: 95%

“…TMP 87. 36.41, TMP 94.163.01, TMP 86.12.11, CMN 8919;Matsumoto & Evans, 2016), likely due to crushing of the palatal region.…”

Section: Palatinementioning

confidence: 99%

See 3 more Smart Citations

Computed tomography analysis of the cranium of Champsosaurus lindoei and implications for the choristoderan neomorphic ossification

et al. 2020

View full text Add to dashboard Cite

Choristoderes are extinct neodiapsid reptiles that are well known for their unusual cranial anatomy, possessing an elongated snout and expanded temporal arches. Although choristodere skulls are well described externally, their internal anatomy remains unknown. An internal description was needed to shed light on peculiarities of the choristodere skull, such as paired gaps on the ventral surface of the skull that may pertain to the fenestra ovalis, and a putative neomorphic ossification in the lateral wall of the braincase. Our goals were: (i) to describe the cranial elements of Champsosaurus lindoei in three dimensions; (ii) to describe paired gaps on the ventral surface of the skull to determine if these are indeed the fenestrae ovales; (iii) to illustrate the morphology of the putative neomorphic bone; and (iv) to consider the possible developmental and functional origins of the neomorph. We examined the cranial anatomy of the choristodere Champsosaurus lindoei (CMN 8920) using high‐resolution micro‐computed tomography scanning. We found that the paired gaps on the ventral surface of the skull do pertain to the fenestrae ovales, an unusual arrangement that may be convergent with some plesiosaurs, some aistopods, and some urodeles. The implications of this morphology in Champsosaurus are unknown and will be the subject of future work. We found that the neomorphic bone is a distinct ossification, but is not part of the wall of the brain cavity or the auditory capsule. Variation in the developmental pathways of cranial bones in living amniotes was surveyed to determine how the neomorphic bone may have developed. We found that the chondrocranium and splanchnocranium show little to no variation across amniotes, and the neomorphic bone is therefore most likely to have developed from the dermatocranium; however, the stapes is a pre‐existing cranial element that is undescribed in choristoderes and may be homologous with the neomorphic bone. If the neomorphic bone is not homologous with the stapes, the neomorph likely developed from the dermatocranium through incomplete fusion of ossification centres from a pre‐existing bone, most likely the parietal. Based on the apparent morphology of the neomorph in Coeruleodraco, the neomorph was probably too small to play a significant structural role in the skull of early choristoderes and it may have arisen through non‐adaptive means. In neochoristoderes, such as Champsosaurus, the neomorph was likely recruited to support the expanded temporal arches.

show abstract

Section: Dentitionsupporting

confidence: 90%

Section: Resultsmentioning

confidence: 74%

Section: Dentitionmentioning

confidence: 95%

“…TMP 87. 36.41, TMP 94.163.01, TMP 86.12.11, CMN 8919;Matsumoto & Evans, 2016), likely due to crushing of the palatal region.…”

Section: Palatinementioning

confidence: 99%

See 2 more Smart Citations

Computed tomography analysis of the cranium of Champsosaurus lindoei and implications for the choristoderan neomorphic ossification

et al. 2020

View full text Add to dashboard Cite

show abstract

“…These animals were primarily aquatic (Katsura, 2010), preying on fish and other aquatic organisms (Matsumoto et al, 2009). The exact phylogenetic position of Choristodera within Diapsida is debated due to the sudden appearance of derived choristoderes in Upper Jurassic deposits, and an absence of specimens from their early evolutionary history (Matsumoto and Evans 2010;Matsumoto and Evans 2016). Of the two main clades within Diapsida (Neodiapsida and Araeoscelidia; Gaffney 1980;Evans 1988), Evans (1990) noted that choristoderes share more features with Neodiapsida, with the exception of the palatal dentition and absence of the mandibular retroarticular process.…”

Section: Introductionmentioning

confidence: 99%

The internal cranial anatomy of Champsosaurus lindoei and its functional implications

Dudgeon¹

View full text Add to dashboard Cite

Although Champsosaurus is well-known in Late Cretaceous and Paleocene deposits of North America, their cranial anatomy is poorly understood. Here, a wellpreserved skull of Champsosaurus lindoei is described in detail using high-resolution micro-CT scanning. This confirms the presence of the putative neomorphic bone, which may be homologous with the pre-existing stapes, or developed through incomplete fusion of dermatocranial ossification centres. The ventral openings on the skull of Champsosaurus relate to the fenestrae ovales, an unusual configuration that may be convergent with other aquatic reptiles. Overall, the endocranial anatomy of Champsosaurus is typical for a basal diapsid. The morphology of the pars inferior of the inner ear suggests that Champsosaurus were capable of detecting sound underwater, and geometric morphometric analyses of the semicircular canals suggests that they were specialized for detecting head movements in an aquatic environment. Taken together, these results suggest that Champsosaurus were well adapted for an aquatic lifestyle.

show abstract

New information on the Jurassic lepidosauromorph Marmoretta oxoniensis

Griffiths

Ford

Benson

et al. 2021

Papers in Palaeontology

Self Cite

View full text Add to dashboard Cite

The earliest known crown-group lepidosaurs are known from the Middle Triassic; however, their stem group is poorly sampled, with only a few representative fossils found. This is partly due to the small size and delicate bones of early stem-lepidosaurs (= non-lepidosaurian lepidosauromorphs), which make both preservation in the fossil record and subsequent discovery less likely. The Middle Jurassic lepidosauromorph Marmoretta oxoniensis is re-examined using high-resolution micro-computed tomography to reveal parts of the skull anatomy that were previously unknown. These include a squamosal, postorbital, more complete parietal, pterygoids, and an articulated posterior section of the mandible. Some differences between this and other Marmoretta specimens were identified as a result, such as the arrangement of palatal teeth and the shape of the parabasisphenoid. The status of Marmoretta as a stem-lepidosaur or stemsquamate has been debated. To evaluate this, we tested the phylogenetic position of Marmoretta by including our new data in an adapted phylogenetic character matrix. We recover Marmoretta as a stem-lepidosaur and sister to Fraxinisaura rozynekae. Our findings support the hypothesis that both taxa belonged to a clade of non-lepidosaurian lepidosauromorphs that co-existed with lepidosaurs into the Middle Jurassic.

show abstract

Morphology and function of the palatal dentition in Choristodera

Cited by 10 publications

References 37 publications

Computed tomography analysis of the cranium of Champsosaurus lindoei and implications for the choristoderan neomorphic ossification

Computed tomography analysis of the cranium of Champsosaurus lindoei and implications for the choristoderan neomorphic ossification

The internal cranial anatomy of Champsosaurus lindoei and its functional implications

New information on the Jurassic lepidosauromorph Marmoretta oxoniensis

Contact Info

Product

Resources

About