Papahu taitapu, gen. et sp. nov., an early Miocene stem odontocete (Cetacea) from New Zealand

The early Miocene is one of the least understood intervals in cetacean evolution. A new early Miocene dolphin described here, Papahu taitapu, gen. et sp. nov. (family incertae sedis, Cetacea, Odontoceti), is from the Kaipuke Formation (21.7–18.7 Ma) of North West Nelson, New Zealand. The holotype of Papahu taitapu includes a skull with an open mesorostral canal, a broad-based rostrum (broken anteriorly), two pairs of premaxillary foramina, a slight bilateral asymmetry at the antorbital notches, a slight intertemporal constriction exposing the temporal fossa and the lateral wall of the braincase in dorsal view, and single-rooted (and probably homodont) teeth. The periotic has an inflated, spherical pars cochlearis and an anterior process with the anterointernal sulcus and a recurved lateral sulcus well developed. The skull size indicates a body length of about 2 m. Papahu taitapu plots cladistically in a cluster of archaic dolphins variously referred to as Platanistoidea or as stem Odontoceti. It matches no family described so far, but cladistic relationships for comparable odontocetes are not yet resolved enough to justify family placement

Juvenile morphology: A clue to the origins of the most mysterious of mysticetes?

The origin of the pygmy right whale (Caperea marginata) has long been one of the most vexing conundrums of marine mammal evolution. The extremely disparate skeletal structure ofCapereaand a patchy fossil record have left morphology and molecules at odds: whereas most morphological analyses allyCapereawith right whales (Balaenidae), most molecular studies instead suggest a close relationship with rorquals (Balaenopteridae) and grey whales (Eschrichtiidae). The morphological evidence supporting aCaperea-balaenid clade consists of several shared features of the skull and mandible, as traditionally observed in adult individuals. Here, we show that at least two of these features, the ascending process of the maxilla and the coronoid process, arise from substantially different precursors early during ontogeny and therefore likely do not represent genuine synapomorphies. Both of these juvenile morphologies have adult counterparts in the fossil record, thus indicating that the ontogenetic variation in the living species may be a genuine reflection of differing ancestral states. This new evidence contradicts previous morphological hypotheses on the origins ofCapereaand may help to reconcile morphological and molecular evidence.Fil: Marx, Felix. University of Otago; Nueva ZelandaFil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagonico; ArgentinaFil: Fordyce, R. Ewan. University of Otago; Nueva ZelandaFil: Boessenecker, Robert W.. University of Otago; Nueva Zeland

A Late Miocene potential neobalaenine mandible from Argentina sheds light on the origins of the living pygmy right whale

The origins and evolutionary relationships of the pygmy right whale (Caperea marginata),the only living member of the Neobalaeninae, have been the subject of a long-standing debate. This phylogenetic uncertainty is compounded by a limited neobalaenine fossil record. Here, we report a Late Miocene mysticete mandible from Patagonia, Argentina and provisionally refer it to Neobalaeninae, gen. et sp. indet. The new material represents only the third report of a fossil neobalaenine, and the first fossil occurrence of this lineage in the southwestern Atlantic. It is also the oldest specimen so far reported, thus corroborating the idea of an early divergence time for neobalaenines.Fil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Dozo, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Marx, Felix G.. University Of Otago; Nueva Zelanda. National Museum of Nature and Science; JapónFil: Fordyce, R. Ewan. University Of Otago; Nueva Zeland

Gigantic mysticete predators roamed the Eocene Southern Ocean

Modern baleen whales (Mysticeti), the largest animals on Earth, arose from small ancestors around 36.4 million years ago (Ma). True gigantism is thought to have arisen late in mysticete history, with species exceeding 10 m unknown prior to 8 Ma. This view is challenged by new fossils from Seymour Island (Isla Marambio), Antarctica, which suggest that enormous whales once roamed the Southern Ocean during the Late Eocene (c. 34 Ma). The new material hints at an unknown species of the archaic mysticete Llanocetus with a total body length of up to 12 m. The latter is comparable to that of extant Omura´s whales (Balaenoptera omurai Wada et al. 2003), and suggests that gigantism has been a re-occurring feature of mysticetes since their very origin. Functional analysis including sharpness and dental wear implies an at least partly raptorial feeding strategy, starkly contrasting with the filtering habit of living whales. The new material markedly expands the size range of archaic mysticetes, and demonstrates that whales achieved considerable disparity shortly after their origin.Fil: Marx, Felix G.. Royal Belgian Institute of Natural Sciences. Directorate Earth and History of Life; Bélgica. Monash University; Australia. Museums Victoria. Geosciences; AustraliaFil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Evans, Alistair R.. Monash University; Australia. Museums Victoria. Geosciences; AustraliaFil: Fordyce, Robert Ewan. University of Otago; Nueva Zelanda. National Museum of Natural History; Estados UnidosFil: Reguero, Marcelo Alfredo. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Hocking, David P.. Monash University; Australia. Museums Victoria. Geosciences; Australi

Radiation of Extant Cetaceans Driven by Restructuring of the Oceans

The remarkable fossil record of whales and dolphins (Cetacea) has made them an exemplar of macroevolution. Although their overall adaptive transition from terrestrial to fully aquatic organisms is well known, this is not true for the radiation of modern whales. Here, we explore the diversification of extant cetaceans by constructing a robust molecular phylogeny that includes 87 of 89 extant species. The phylogeny and divergence times are derived from nuclear and mitochondrial markers, calibrated with fossils. We find that the toothed whales are monophyletic, suggesting that echolocation evolved only once early in that lineage some 36–34 Ma. The rorqual family (Balaenopteridae) is restored with the exclusion of the gray whale, suggesting that gulp feeding evolved 18–16 Ma. Delphinida, comprising all living dolphins and porpoises other than the Ganges/Indus dolphins, originated about 26 Ma; it contains the taxonomically rich delphinids, which began diversifying less than 11 Ma. We tested 2 hypothesized drivers of the extant cetacean radiation by assessing the tempo of lineage accumulation through time. We find no support for a rapid burst of speciation early in the history of extant whales, contrasting with expectations of an adaptive radiation model. However, we do find support for increased diversification rates during periods of pronounced physical restructuring of the oceans. The results imply that paleogeographic and paleoceanographic changes, such as closure of major seaways, have influenced the dynamics of radiation in extant cetaceans

Cetaceans have complex brains for complex cognition

MEDLINE® is the source for the citation and abstract of this record.Peer reviewedPublisher PD

Waipatia maerewhenua, new genus and new species (Waipatiidae, new family), an archaic Late Oligocene dolphin (Cetacea: Odontoceti: Platanistoidea) from New Zealand

Volume: 29Start Page: 147End Page: 17

The morphology and systematics of New Zealand fossil cetacea

Previous work on New Zealand fossil Cetacea is reviewed. The formally described specimens of Kekenodon onamata, Squalodon serratus, a protosqualodontid, Austrosqualodon trirhizodonta, Prosqualodon hamiltoni, Prosqualodon marplesi, Squalodon andrewi, Microcetus hectori, Tangaroasaurus kakanuiensis, Phocaenopsis mantelli, an "archaeocete" braincast, an odontocete braincast, Mauicetus parki, M. brevicollis, M. lophocephalus, and M. waitakiensis are redescribed and/or reappraised. Other New Zealand fossil Cetacea, predominantly Oligocene in age, are redescribed. Three Late Eocene specimens include aff. Dorudon, and indicate 1 the early presence of archaeocetes in New Zealand. Four Early Oligocene Cetacea comprise one Cetacea incertae sedis, the earliest recorded odontocete, and. the two earliest recorded mysticetes. Evolution of odontocetes and mysticetesin southern oceans at this time reflects the advent of new feeding strategies triggered by changes in oceanic trophic regimes. Mid Oligocene Cetacea include archaeocetes {Kekenodon}, odontocetes {e.g. squalodonts} and mysticetes {e.g. "Mauicetus"}. Mysticete radiation was influenced further by trophic resource changes. The Late Oligocene fauna is diverse. Archaeocetes are not recorded in New Zealand, but occur in Australia {Mammalodon}. Squalodontid odontocetes include Prosqualodon s. s., "P." hamil toni, "P." marplesi, a Phoberodon-like form, and indeterminate taxa. Nonsqualodonts include eurhinodelphinids{?} and platanistoids{?}, and mysticetes include Mauicetus parki {Cetotheriidae} and an uncertain number of other cetotheres. Late Oligocene Cetacea are more abundant than their antecedents, and similarities with those from elsewhere suggest a diverse and cosmopolitan global fauna. The relatively poorly studied Neogene fauna comprises squalodonts, platanistoids?, ziphioids, delphinoids, indeterminate odontocetes, and indeterminate mysticetes. Amongst more recent forms are mysticetes and delphinids of modern appearance. Some phases of cetacean evolution were saltatory, not gradualistic. The Oligocene was not necessarily a time of low diversity, especially in the Southwest Pacific. Cetacean evolution then {e.g. the appearance of odontocetes and mysticetes} was rapid, and linked with Southern Hemisphere oceanic changes

A review of the Australian fossil Cetacea

Volume: 43Start Page: 43End Page: 5