Occipital Ossification of Balaenopteroid Mysticetes

Walsh, Breda M.; Berta, Annalisa

doi:10.1002/ar.21340

Cited by 51 publications

(48 citation statements)

References 17 publications

(31 reference statements)

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“…14C), and incompletely ossified vertebrae. An unfused basioccipitalÀexoccipital synchondrosis suggests that OU 12918 is a young juvenile (Walsh & Berta 2011), but an unfused median frontal suture is present even in adult eomysticetids (Tohoraata, Tokarahia, Waharoa; Boessenecker & Fordyce 2015a, b, c). Furthermore, histological examination of the sectioned rib of OU 12918 shows mostly woven bone, indicating minimal bone remodelling and presumably a young ontogenetic age (Fig.…”

Section: Discussionmentioning

confidence: 99%

A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea)

Boessenecker

Fordyce

2016

Journal of Systematic Palaeontology

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Eomysticetids represent a worldwide, short-lived radiation of archaic baleen-bearing mysticetes that elucidate morphofunctional shifts and ontogenetic change amongst early Neoceti. Fossils of eomysticetids are now recorded from Oligocene marine rocks along the margins of the North Pacific (Japan), North Atlantic (South Carolina), and the Southern Ocean (New Zealand). The assemblage from New Zealand is diverse, with five species in three genera present during the Duntroonian stage (Chattian, 27.3À25.2 Ma). A new genus and species of eomysticetid from the lower Kokoamu Greensand of New Zealand, Matapa waihao gen. et sp. nov., increases the known diversity of Southern Hemisphere eomysticetids. Matapa uniquely exhibits a rounded margin of the occipital shield, and shares a mosaic of features seen in Northern Hemisphere eomysticetids such as a large squamosal prominence, an inflated and posteriorly rounded paroccipital process, and a double-faced posterior bullar facet with longitudinal ridges. The holotype specimen of Matapa waihao is ontogenetically immature, but ontogenetically static tympanoperiotic characters that diagnose this new species are shared by referred adult specimens. Matapa is uppermost Whaingaroan (28.1À27.3 Ma) in age, the oldest eomysticetid from New Zealand. Fossils of Matapa are recovered from both the modern west and east coast of New Zealand which, during the Oligocene, were on the margin of the Southern Ocean. Inclusion of Matapa within an earlier published cladistic analysis recovers Matapa as the earliest diverging member of the New Zealand eomysticetid clade, and confirms eomysticetid monophyly. The taxonomy, morphology and geochronological age of all known eomysticetids are reviewed.http://zoobank.org/urn:lsid:zoobank.org:pub:EE1CB5CC-618B-4ABA-9D97-5B9DEDD3470E

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Section: Discussionmentioning

confidence: 99%

A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea)

Boessenecker

Fordyce

2016

Journal of Systematic Palaeontology

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“…We judged skeletal maturity on the basis of suture fusion in the cranium and the degree of porosity on the occipital condyles (see more references and details in Supplemental Information). Recent work (Walsh and Berta 2011) has borne the validity of such qualitative metrics for Balaenopteroidea, and we presume that they broadly apply to all Neoceti, in the absence of any quantitative evidence otherwise. Lastly, we averaged all specimen values within a species, irrespective of sex.…”

Section: Taxon Samplingmentioning

confidence: 76%

Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record

2011

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Living cetaceans exhibit interspecific size ranging across several orders of magnitude, and rank among the largest vertebrates ever. Details of how cetaceans evolved different body sizes, however, remain obscure, because they lack basic morphological proxies that have been traditionally used in other fossil vertebrates. Here, we reconstruct the body size of extinct crown group cetaceans (Neoceti) using different regression methods on extant skull and length data, in a phylogenetic context. Because most fossil cetaceans are fragmentary, we developed regression equations to predict total length based on cranial metrics that are preserved on most fossil crania. The resultant regression equations are based on a database of skull and length data from most extant lineages of cetaceans (n=45 species; 272 specimens), sampling all living mysticete genera and all major clades of odontocetes. In generating predictive equations, we compared both conventional species data regression and independent contrast regression methods, as well as single trait predictors and a new approach that combines the advantages of a partial least squares (PLS) multivariate regression with independent contrasts. This last approach leverages the predictive power of using multiple correlated proxies. Lastly, we used the rare occurrences of fossil cetaceans with preserved total lengths to test the performance of our predictive equations for reconstructing body size from skull measurements alone. Our results demonstrate that incorporating information about phylogenetic relationships and multiple cranial measures in PLS scaling studies increases the accuracy of reconstructed body size, most notably by reducing prediction intervals by more than 70%. With this empirical foundation, we highlight the outline of major features in the evolution of body size for Neoceti and future opportunities to use these metrics for paleobiological questions.

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“…The holotype skull of Eubalaena ianitrix , however, shows sutural morphologies and general robustness inconsistent with the general osteological features of newborn and early juvenile individuals (e.g., occipital joints not closed, presence of spongy bone; see Walsh & Berta, 2011). Rather, its robust muscular attachments on the supraoccipital and the degree of fusion at the frontoparietal (coronal) and parietal–squamosal sutures suggests that its age was older than one year.…”

Section: Discussionmentioning

confidence: 93%

Revision of “Balaena”belgicareveals a new right whale species, the possible ancestry of the northern right whale,Eubalaena glacialis, and the ages of divergence for the living right whale species

Bisconti

Lambert

Bosselaers

2017

PeerJ

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In 1941, Abel established Balaena belgica based on a series of fused cervical vertebrae and citing other cranial fragments from the late Neogene of the Antwerp harbor (northern Belgium). Later, Plisnier-Ladame & Quinet (1969) added a neurocranium and other skeletal remains from the same area to this species. Recently, the neurocranium was re-assigned to the genus Eubalaena thanks to newer phylogenetic analyses. Here, a new description is provided of materials previously assigned to “Balaena” belgica together with taxonomic revisions. Our work suggests that the cervical complex originally designated as the type of “Balaena” belgica is too poorly preserved to be used as such and is assigned to Balaenidae gen. et sp. indet., thus making “Balaena” belgica a nomen dubium. In addition to the neurocranium, the other remains consist in a fragment of maxilla assigned to Balaenidae gen. et sp. indet. and in a humerus assigned to Eubalaena sp. Discovered in the Kruisschans Sands Member of the Lillo Formation (3.2–2.8 Ma, Piacenzian, Late Pliocene), the neurocranium is designated as the holotype of the new species Eubalaena ianitrix. Our phylogenetic analysis supports a sister-group relationship of Eubalaena ianitrix and Eubalaena glacialis, and helps constraining the ages of origin for balaenid clades. Ecological and phylogenetic data suggest that Eubalaena ianitrix may represent the direct ancestor of Eubalaena glacialis, the latter having evolved through phyletic transformation including body size increase during the temperature decline of the Late Pliocene.

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Occipital Ossification of Balaenopteroid Mysticetes

Cited by 51 publications

References 17 publications

A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea)

A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea)

Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record

Revision of “Balaena”belgicareveals a new right whale species, the possible ancestry of the northern right whale,Eubalaena glacialis, and the ages of divergence for the living right whale species

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