''Horopeta'' is a genus of

baleen whale Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...

from the Late Oligocene (

Chattian The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

)

Kokoamu Greensand The Kokoamu Greensand is a geological formation found in New Zealand. It is a fossil-bearing, late Oligocene, greensand rock unit of the eastern South Island, especially the Waitaki District of North Otago and the southern Canterbury region. Th ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Description

''Horopeta'' can be distinguished from other balaenomorphs in the following characters: base of frontal sloping moderately from skull midline; parietal considerably exposed at sagittal crest; parietal largely exposed at sagittal crest; unfused and short posterior process of periotic and tympanic bulla; prominent superior process of periotic; presence of elliptical foramen and sigmoidal cavity in tympanic bulla; unfused and short posterior processes of periotic and tympanic bulla; a distinct pedicle plate situated in fovea epitubaria; presence of horizontal cleft, elliptical foramen, and sigmoidal cavity in tympanic bulla.Cheng-Hsiu Tsai; R. Ewan Fordyce (2015). "The Earliest Gulp-Feeding Mysticete (Cetacea: Mysticeti) from the Oligocene of New Zealand". Journal of Mammalian Evolution 22 (4): 535–560. doi:10.1007/s10914-015-9290-0.

Classification

Initial cladistic analysis recovered ''Horopeta'' as either a basal balaenomorph or a basal cetotheriid, although the describers noted that the juvenile nature of the holotype might influence its cladistic position within Chaeomysticeti. Later cladistic analyses corroborated the placement of ''Horopeta'' outside crown Mysticeti.Carlos Mauricio Peredo; Mark D. Uhen (2016). "A new basal chaeomysticete (Mammalia: Cetacea) from the Late Oligocene Pysht Formation of Washington, USA". Papers in Palaeontology. Online edition. doi:10.1002/spp2.1051

Paleobiology

Based on the structure of the jaw, ''Horopeta'' was one of the earliest chaeomysticetes capable of gulp-feeding as in extant mysticetes. The same deposits that yielded ''Horopeta'' have also yielded the primitive odontocetes '' Awamokoa'', '' Austrosqualodon'', ''

Otekaikea ''Otekaikea'' is an extinct genus of toothed whale closely related to ''Waipatia''. It is known from the late Oligocene (Chattian) of New Zealand. Description ''Otekaikea'' is a medium-sized odontocete similar to ''Waipatia'' in the following ...

'', and ''

Waipatia ''Waipatia'' is an extinct genus of odontocetes from the late Oligocene (Chattian) of New Zealand. Taxonomy The type species, ''Waipatia maerewhenua'' is known from a single skull found near 45° South in Otago Otago (, ; ) is a regions ...

'', the eomysticetids '' Matapanui'', '' Tohoraata'', '' Tokarahia'', and ''

Waharoa A waharoa is an entrance gateway to a marae complex in New Zealand. Waharoa may refer to: * ''Waharoa'' (Aotea Square sculpture) (1990), a sculpture by Selwyn Muru in Aotea Square, Auckland * ''Waharoa'' (1990), a sculptural entranceway to the Auc ...

'', and the balaenomorphs '' Mauicetus'' and '' Whakakai''.

References

{{Taxonbar, from=Q28182611 Oligocene cetaceans Extinct animals of New Zealand Monotypic prehistoric cetacean genera