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From Problem Taxa to Problem Solver: A New Miocene Family, Tranatocetidae, Brings Perspective on Baleen Whale Evolution.

Gol'din P, Steeman ME - PLoS ONE (2015)

Bottom Line: It was found to represent not only a new genus, Tranatocetus gen. nov., but also a new family; Tranatocetidae.Inclusion of problematic taxa like Tranatocetus argillarius in phylogenies brings new understanding of the distribution and diagnostic value of character traits.This underlines the need for re-examination of earlier described specimens in the light of the wealth of new information published in later years.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural History and Palaeontology, The Museum of Southern Jutland, Lergravsvej 2, 6510, Gram, Denmark.

ABSTRACT
Miocene baleen whales were highly diverse and included tens of genera. However, their taxonomy and phylogeny, as well as relationships with living whales, are still a subject of controversy. Here, "Mesocetus" argillarius, a poorly known specimen from Denmark, is redescribed with a focus on the cranial anatomy. It was found to represent not only a new genus, Tranatocetus gen. nov., but also a new family; Tranatocetidae. The whales of this family have the rostral bones either overriding or dividing the frontals; the rostral bones are contacting the parietals and nasals dividing the maxillae on the vertex; the occipital shield is dorsoventrally bent. The tympanic bulla is particularly characteristic of this family featuring a short, narrow anterior portion with a rounded or squared anterior end and a wider and higher posterior portion that is swollen in the posteroventral area. A phylogenetic analysis including 51 taxa supports a monophyletic group comprising most Neogene and modern whales, with Tranatocetidae being possibly closer related to Balaenopteridae (rorquals) than to Cetotheriidae. Tranatocetidae exhibit a charahteristic bulla shape. In fact, all Neogene and modern mysticete families examined have a unique shape of the tympanic bulla that is diagnostic at family-level. Inclusion of problematic taxa like Tranatocetus argillarius in phylogenies brings new understanding of the distribution and diagnostic value of character traits. This underlines the need for re-examination of earlier described specimens in the light of the wealth of new information published in later years.

No MeSH data available.


Related in: MedlinePlus

Right periotic bone of Tranatocetus argillarius, MGUH VP 2319.A, ventral view. B, posterior view (cropped image).
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pone.0135500.g006: Right periotic bone of Tranatocetus argillarius, MGUH VP 2319.A, ventral view. B, posterior view (cropped image).

Mentions: The periotic body is significantly larger than the pars cochlearis (Fig 6). The pars cochlearis is small, anteroposteriorly short and bulges slightly ventral to fenestra rotunda. The anterior process of the periotic is sub-triangular with a poorly developed lateral flange (or lateral tuberosity). The mallear fossa is small, round and shallow. The posterior cochlear crest (caudal tympanic process) is short and the stylomastoid fossa is shallow. The groove for the tensor tympani muscle is shallow. The posterolaterally directed posterior process of the tympanoperiotic is long, widening distally with a small exposure on the posterolateral wall of the skull. The tympanic bulla is pyriform in ventral view (Fig 7). The narrow and low anterior portion is short with a rounded anterior end, while the posterior portion is larger in all dimensions. Particularly swollen is the posteroventral area lateral to the base of the posterolaterally directed sigmoid process. The lateral furrow is deep and the groove posterior to the sigmoid process is shallow (see also [5]). In ventrolateral view, the conical process, as preserved, is distinctly high. In medial view, the main ridge is more developed than the involucral ridge. The ridges converge toward the anterior end. The lateral lobe extends more posteriorly than the medial one. In dorsal view, the involucrum is high and convex.


From Problem Taxa to Problem Solver: A New Miocene Family, Tranatocetidae, Brings Perspective on Baleen Whale Evolution.

Gol'din P, Steeman ME - PLoS ONE (2015)

Right periotic bone of Tranatocetus argillarius, MGUH VP 2319.A, ventral view. B, posterior view (cropped image).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558012&req=5

pone.0135500.g006: Right periotic bone of Tranatocetus argillarius, MGUH VP 2319.A, ventral view. B, posterior view (cropped image).
Mentions: The periotic body is significantly larger than the pars cochlearis (Fig 6). The pars cochlearis is small, anteroposteriorly short and bulges slightly ventral to fenestra rotunda. The anterior process of the periotic is sub-triangular with a poorly developed lateral flange (or lateral tuberosity). The mallear fossa is small, round and shallow. The posterior cochlear crest (caudal tympanic process) is short and the stylomastoid fossa is shallow. The groove for the tensor tympani muscle is shallow. The posterolaterally directed posterior process of the tympanoperiotic is long, widening distally with a small exposure on the posterolateral wall of the skull. The tympanic bulla is pyriform in ventral view (Fig 7). The narrow and low anterior portion is short with a rounded anterior end, while the posterior portion is larger in all dimensions. Particularly swollen is the posteroventral area lateral to the base of the posterolaterally directed sigmoid process. The lateral furrow is deep and the groove posterior to the sigmoid process is shallow (see also [5]). In ventrolateral view, the conical process, as preserved, is distinctly high. In medial view, the main ridge is more developed than the involucral ridge. The ridges converge toward the anterior end. The lateral lobe extends more posteriorly than the medial one. In dorsal view, the involucrum is high and convex.

Bottom Line: It was found to represent not only a new genus, Tranatocetus gen. nov., but also a new family; Tranatocetidae.Inclusion of problematic taxa like Tranatocetus argillarius in phylogenies brings new understanding of the distribution and diagnostic value of character traits.This underlines the need for re-examination of earlier described specimens in the light of the wealth of new information published in later years.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural History and Palaeontology, The Museum of Southern Jutland, Lergravsvej 2, 6510, Gram, Denmark.

ABSTRACT
Miocene baleen whales were highly diverse and included tens of genera. However, their taxonomy and phylogeny, as well as relationships with living whales, are still a subject of controversy. Here, "Mesocetus" argillarius, a poorly known specimen from Denmark, is redescribed with a focus on the cranial anatomy. It was found to represent not only a new genus, Tranatocetus gen. nov., but also a new family; Tranatocetidae. The whales of this family have the rostral bones either overriding or dividing the frontals; the rostral bones are contacting the parietals and nasals dividing the maxillae on the vertex; the occipital shield is dorsoventrally bent. The tympanic bulla is particularly characteristic of this family featuring a short, narrow anterior portion with a rounded or squared anterior end and a wider and higher posterior portion that is swollen in the posteroventral area. A phylogenetic analysis including 51 taxa supports a monophyletic group comprising most Neogene and modern whales, with Tranatocetidae being possibly closer related to Balaenopteridae (rorquals) than to Cetotheriidae. Tranatocetidae exhibit a charahteristic bulla shape. In fact, all Neogene and modern mysticete families examined have a unique shape of the tympanic bulla that is diagnostic at family-level. Inclusion of problematic taxa like Tranatocetus argillarius in phylogenies brings new understanding of the distribution and diagnostic value of character traits. This underlines the need for re-examination of earlier described specimens in the light of the wealth of new information published in later years.

No MeSH data available.


Related in: MedlinePlus