Abstract
ABSTRACT 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. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Highlights
The reported record of early Miocene Odontoceti (Cetacea) implies a high taxonomic diversity, consistent with the idea that odontocetes started to radiate during the Oligocene and peaked in diversity in the middle to late Miocene (Uhen and Pyenson, 2007; Marx and Uhen, 2010)
This seemingly high early Miocene family-level diversity is somewhat illusory: the families are represented by few genera and species, with some species known from a single fossil
We suggest, reflects several issues, including (1) loss of type material and/or uncertainty about details of figured material (P. davidis, A. pygmaeus, P. kazakhstanicus); (2) limited or no access to details of character-rich tympanoperiotics and/or adjacent details of the basicranium (P. davidis, A. pygmaeus, P. kazakhstanicus, S. emlongi); and (3) limited taxonomic sampling of basal Odontoceti
Summary
The reported record of early Miocene Odontoceti (Cetacea) implies a high taxonomic diversity, consistent with the idea that odontocetes started to radiate during the Oligocene and peaked in diversity in the middle to late Miocene (Uhen and Pyenson, 2007; Marx and Uhen, 2010). Opinions vary on the number and content of families of early Miocene odontocetes, but recent authors have listed up to 10 families, and/or additional stem clusters, attributed to four superfamilies: (1) Platanistoidea (sensu Muizon, 1987, variously including Dalpiazinidae, Squalodelphinidae, Squalodontidae, Prosqualodontidae, and Allodelphinidae); (2) Eurhinodelphinoidea (sensu Muizon, 1991, with Eoplatanistidae and Eurhinodelphinidae); (3) Physeteroidea (sensu Lambert, 2008, variously including Kogiidae and Physeteridae); and (4) Delphinoidea (sensu Muizon, 1988a, with Kentriodontidae) This seemingly high early Miocene family-level diversity is somewhat illusory: the families are represented by few genera and species, with some species known from a single fossil. The enigmatic Eurhinodelphinoidea has been tentatively placed as a sister clade to Delphinida (Muizon, 1991) and Ziphiidae (Lambert, 2005), but its affinities are poorly understood (Fordyce and Muizon, 2001)
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