Decrease in tooth count in melon-headed whales

2016 ◽  
Vol 300 (1) ◽  
pp. 8-17 ◽  
Author(s):  
N. Kurihara ◽  
M. Amano ◽  
T. K. Yamada
Keyword(s):  
Tooth Count

scholarly journals Evidence of macrophagous teleosaurid crocodylomorphs in the Corallian Group (Oxfordian, Late Jurassic) of the UK

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1497 ◽  
Author(s):  
Davide Foffa ◽  
Mark T. Young ◽  
Stephen L. Brusatte
Keyword(s):  
Fossil Record ◽  
Late Jurassic ◽  
Time Span ◽  
Specific Level ◽  
Lower Jaw ◽  
Abundance And Diversity ◽  
The Uk ◽  
Clay Formation ◽  
Tooth Count

Teleosaurids were a group of semi-aquatic crocodylomorphs with a fossil record that spanned the Jurassic Period. In the UK, abundant specimens are known from the Oxford Clay Formation (OCF, Callovian to lower Oxfordian), but are very rare in the Kimmeridge Clay Formation (KCF, Kimmeridgian to lower Tithonian), despite their abundance in some contemporaneous deposits in continental Europe. Unfortunately, due to the paucity of material from the intermediate ‘Corallian Gap’ (middle to upper Oxfordian), we lack an understanding of how and why teleosaurid taxic abundance and diversity declined from the OCF to the KCF. The recognition of an incomplete teleosaurid lower jaw from the Corallian of Weymouth (Dorset, UK) begins to rectify this. The vertically oriented dentition, blunt tooth apices, intense enamel ornamentation that shifts to an anastomosed pattern apically, and deep reception pits on the dentary unambiguously demonstrates the affinity of this specimen with an unnamed sub-clade of macrophagous/durophagous teleosaurids (‘Steneosaurus’obtusidens+Machimosaurus). The high symphyseal tooth count allows us to exclude the specimen fromM. hugiiandM. mosae, but in absence of more diagnostic material we cannot unambiguously assign DORCM G.3939 to a more specific level. Nevertheless, this specimen represents the first mandibular material referable to Teleosauridae from the poorly sampled middle-upper Oxfordian time-span in the UK.

A new glyptosaurine lizard from the earliest Eocene of Dormaal, Belgium

2012 ◽  
Vol 183 (6) ◽  
pp. 627-633 ◽  
Author(s):  
Robert M. Sullivan ◽  
Marc Augé ◽  
Eric Wille ◽  
Richard Smith
Keyword(s):  
North America ◽  
Western Europe ◽  
Reference Level ◽  
New Taxon ◽  
Early Eocene ◽  
Lower Eocene ◽  
Lower Tooth ◽  
Late Paleocene ◽  
Sudden Appearance ◽  
Tooth Count

Abstract A new glyptosaurine lizard ?Placosaurus ragei, n. sp., is recognized as being distinct from Paraplacosauriops quercyi in having a lightly built dentary, incipient heterodont teeth, lower tooth count (19), and teeth that are more gracile compared to other European glyptosaurine lizards. ?Placosaurus ragei also differs from “Placosaurus” europaeus, which has a prominent homodont dentition and is more massive. A second specimen, an isolated, nearly complete parietal, partly covered with hexagonal and polygonal osteoderms, is referable to the European glyptosaurin Placosaurus and is provisionally referred to the species ?Placosaurus ragei. A third specimen, an incomplete right frontal fragment of an indeterminate “melanosaurin,” may represent a new taxon, or may be referable to the well-known Western European taxon Placosauriops. Taxa pertaining to both tribes (Glyptosaurini and “Melanosaurini”) of glyptosaurine lizards have been recovered from the lower Eocene deposits of Dormaal, Belgium. Their apparent sudden appearance is interpreted as marking entry into western Europe. The Dormaal locality has been correlated to reference level MP7 and thus is considered to be of early Eocene age. Glyptosaurine lizards probably dispersed into western Europe, from North America, through the Greenland bridge during late Paleocene/early Eocene time.

scholarly journals The Influence of Diet, Exercise and Education Level During Pregnancy on Child Cavities and Tooth Eruption

2021 ◽  
pp. 1-8
Author(s):  
Linda E May ◽  
Alexis Brown ◽  
Alex Kordis ◽  
Christopher Cotterill ◽  
Vanessa Pardi ◽  
...  
Keyword(s):  
Maternal Education ◽  
Dental Health ◽  
Exercise Duration ◽  
Education Level ◽  
Tooth Eruption ◽  
Primary Tooth ◽  
Caries Risk ◽  
Dairy Foods ◽  
Mother's Educational Level ◽  
Tooth Count

Objectives: This study’s objective was to evaluate if exercise during pregnancy, a healthy diet rich in polyunsaturated fatty acids and calcium, and the mother’s educational level influenced the dental health measures of caries risk and tooth eruption of their offspring. Methods: Women with children 6 years and younger completed questionnaires regarding PA and diet (PUFA-rich, calcium-rich (Ca) dairy foods) during pregnancy and education level prior to their child’s dental examination. T-tests were used to compare exercisers and non-exercisers; correlation and regression analyses were conducted to determine relationships and predictors of child dental health, respectively. Results: Eighty-two mother-child pairs were analysed. Exercisers had trends of increased PUFA (p=0.07) and Ca-rich dairy foods (p=0.12) to non-exercisers during pregnancy. Ca-rich dairy foods during pregnancy had positive associations with primary tooth count (p=0.004), mixed surface count (p=0.02), and tooth eruption (p=0.04). Controlling for maternal education and exercise, tooth eruption was predicted by PUFA summary and cheese consumption while dairy summary predicted primary tooth count; caries risk was predicted by maternal education; primary surface caries was associated with exercise duration. Conclusion: During pregnancy, calcium-rich dairy and PUFA-rich foods influenced child tooth eruption and thus tooth count, while exercise duration was associated with primary surface caries. Maternal education was associated with lower caries risk. Our findings support educating women on calcium intake and appropriate exercise levels during pregnancy, plus oral health counseling for their child.

scholarly journals A toothless dwarf dolphin (Odontoceti: Xenorophidae) points to explosive feeding diversification of modern whales (Neoceti)

2017 ◽  
Author(s):  
Robert Boessenecker ◽  
Danielle Fraser ◽  
Morgan Churchill ◽  
Jonathan Geisler
Keyword(s):  
Phylogenetic Analysis ◽  
South Carolina ◽  
Feeding Behaviour ◽  
Stabilizing Selection ◽  
Suction Feeding ◽  
Feeding Mode ◽  
Milk Teeth ◽  
Feeding Morphology ◽  
Tooth Count

Toothed whales (Odontoceti) are adapted for catching prey underwater and possess some of the most derived feeding specializations of all mammals, including the loss of milk teeth (monophyodonty), high tooth count (polydonty), and the loss of discrete tooth classes (homodonty). Many extant odontocetes possess some combination of short, broad rostra, reduced tooth counts, fleshy lips, and enlarged hyoid bones - all adaptations for suction feeding upon fish and squid. We report a new fossil odontocete from the Oligocene (~30 Ma) of South Carolina (Inermorostrum xenops, gen. et sp. nov.) that possesses adaptations for suction feeding: toothlessness and a shortened rostrum (brevirostry). Enlarged foramina on the rostrum suggest the presence of enlarged lips or perhaps vibrissae. Phylogenetic analysis firmly places Inermorostrum within the Xenorophidae, an early diverging odontocete clade typified by long-snouted, heterodont dolphins. Inermorostrum is the earliest obligate suction feeder within the Odontoceti, a feeding mode that independently evolved several times within the clade. Analysis of macroevolutionary trends in rostral shape indicate stabilizing selection around an optimum rostral shape over the course of odontocete evolution, and a post-Eocene explosion in feeding morphology, heralding the diversity of feeding behaviour amongst modern Odontoceti.

scholarly journals New specimen and revision of the late Jurassic teleosaurid 'Steneosaurus’ megarhinus

2015 ◽  
Author(s):  
Davide Foffa ◽  
Mark T Young ◽  
Stephen L Brusatte ◽  
Lorna Steel
Keyword(s):  
Fossil Record ◽  
Late Jurassic ◽  
Anterior Margin ◽  
Unique Combination ◽  
Coastal Marine ◽  
Successful Group ◽  
Clay Formation ◽  
Tooth Count

Teleosaurids were a successful group of semi-aquatic crocodylomorphs that were an abundant part of coastal marine/lagoonal faunas during the Jurassic. Their fossil record suggests that the group declined in diversity and abundance during the Late Jurassic. 'Steneosaurus’ megarhinus (Hulke, 1871) from the Kimmeridge Clay Formation is a little known gracile longirostrine species of teleosaurid from the Late Jurassic (late Kimmeridgian). The holotype, an incomplete snout NHMUK PV OR43086, was firstly described by Hulke in 1871. Since then only one other specimen, an almost complete skull from the slightly older Aulacostephanus eudoxus Sub-Boreal ammonite Zone of “La Crouzette”, Francoulès (Quercy, France), has been referred to this species. Here, we describe, DORCM G.5067i-v, the anterior rostrum of a teleosaurid from the same horizon and locality as the holotype. We demonstrate that DORCM G.5067i-v is referable to Steneosaurus’ megarhinus based on a unique combination of characters, which include: strongly ventrally deflected anterior margin of the premaxilla; five premaxillary alveoli, the caudal-most being considerably reduced in size; anterodorsally oriented external nares; conical teeth bearing carinae which are only visible on the apical third of the crown. Importantly, the tooth count, shape of external nares and strong premaxillary deflection distinguish Steneosaurus’ megarhinus from all other Middle and Late Jurassic longirostrine teleosaurids. Some of these characteristics resemble those seen in pholidosaurids, suggesting some convergence between these clades.

scholarly journals Evidence of macrophagous teleosaurids in the Corallian Group (Oxfordian, Late Jurassic) of the UK

2015 ◽  
Author(s):  
Davide Foffa ◽  
Mark T Young ◽  
Stephen L Brusatte
Keyword(s):  
Fossil Record ◽  
Late Jurassic ◽  
Time Span ◽  
Specific Level ◽  
Northern France ◽  
Lower Jaw ◽  
Abundance And Diversity ◽  
The Uk ◽  
Tooth Count

Teleosaurids were a semi-aquatic group of crocodylomorphs with a fossil record that spanned the Jurassic Period. Abundant specimens are known from Oxford Clay (OCF, Callovian to lower Oxfordian) and Kimmeridge Clay (KCF, Kimmeridgian to lower Tithonian) Formations of the UK, and contemporaneous deposits in northern France. Unfortunately, due to the paucity of material from the intermediate ‘Corallian Gap’(middle to upper Oxfordian), we lack an understanding of how and why teleosaurid taxic abundance and diversity declined from the OCF to the KCF. Our discovery of an incomplete teleosaurid lower jaw from the Corallian of Weymouth (Dorset, UK) begins to help rectify this. The vertically oriented dentition, blunt tooth apices, and intense enamel ornamentation that shifts apical to an anastomosed pattern, and deep reception pits on dentary unambiguously demonstrates the affinity of this specimen with a sub-clade of macrophagous/durophagous teleosaurids ('Steneosaurus' obtusidens + Machimosaurus>). The high symphyseal tooth count allows us to exclude the specimen from M. hugii and M. mosae, but in absence of more diagnostic material we cannot unambiguously assign the specimen to a more specific level. Nevertheless, this specimen represents the first UK mandibular material referable to Teleosauridae from this poorly known time-span.

scholarly journals Evidence of macrophagous teleosaurids in the Corallian Group (Oxfordian, Late Jurassic) of the UK

2015 ◽  
Author(s):  
Davide Foffa ◽  
Mark T Young ◽  
Stephen L Brusatte
Keyword(s):  
Fossil Record ◽  
Late Jurassic ◽  
Time Span ◽  
Specific Level ◽  
Northern France ◽  
Lower Jaw ◽  
Abundance And Diversity ◽  
The Uk ◽  
Tooth Count

Teleosaurids were a semi-aquatic group of crocodylomorphs with a fossil record that spanned the Jurassic Period. Abundant specimens are known from Oxford Clay (OCF, Callovian to lower Oxfordian) and Kimmeridge Clay (KCF, Kimmeridgian to lower Tithonian) Formations of the UK, and contemporaneous deposits in northern France. Unfortunately, due to the paucity of material from the intermediate ‘Corallian Gap’(middle to upper Oxfordian), we lack an understanding of how and why teleosaurid taxic abundance and diversity declined from the OCF to the KCF. Our discovery of an incomplete teleosaurid lower jaw from the Corallian of Weymouth (Dorset, UK) begins to help rectify this. The vertically oriented dentition, blunt tooth apices, and intense enamel ornamentation that shifts apical to an anastomosed pattern, and deep reception pits on dentary unambiguously demonstrates the affinity of this specimen with a sub-clade of macrophagous/durophagous teleosaurids ('Steneosaurus' obtusidens + Machimosaurus>). The high symphyseal tooth count allows us to exclude the specimen from M. hugii and M. mosae, but in absence of more diagnostic material we cannot unambiguously assign the specimen to a more specific level. Nevertheless, this specimen represents the first UK mandibular material referable to Teleosauridae from this poorly known time-span.

A new younginid (Reptilia: Eosuchia) from the Upper Permian of Madagascar

1980 ◽  
Vol 17 (4) ◽  
pp. 500-511 ◽  
Author(s):  
Philip J. Currie
Keyword(s):  
New Genus ◽  
Type Specimen ◽  
Upper Permian ◽  
New Genus And Species ◽  
Maxillary Tooth ◽  
The Family ◽  
Anatomical Information ◽  
Tooth Count ◽  
Partial Skeleton

Acerosodontosaurus piveteaui, a new genus and species of primitive diapsid reptile of the Family Younginidae, is based upon a partial skull and partial skeleton from Upper Permian strata of the République Démocratique de Madagascar. Morphologically, Acerosodontosaurus is closer to Youngina than any other known early diapsid. It can be distinguished from Youngina by a higher maxillary tooth count, a broader skull in the antorbital region, a broader puboischiatic plate, and a longer iliac blade. The type specimen is more mature than known specimens of Youngina, and furnishes anatomical information not reported in other younginid specimens.

scholarly journals Tooth Count Variation in the Japanese Salamanders

1983 ◽  
Vol 10 (2) ◽  
pp. 39-41
Author(s):  
Masafumi MATSUI ◽  
Shingo TANABE ◽  
Yasuhiro KOKURYO
Keyword(s):  
Tooth Count
Sign in / Sign up

Export Citation Format

Share Document