Balaenoptera


Balaenoptera is a genus of rorquals containing eight extant species. Balaenoptera comprises all but two of the extant species in its family ; the genus is currently polyphyletic, with the two aforementioned species being phylogenetically nested within it.
This genus is known in the fossil records from the Neogene to the Quaternary.
File: Balaenopteridae - Balaenoptera acutorostrata cuvieri.JPG|thumb|240px|Fossil of Balaenoptera acutorostrata cuvieri from the Pliocene of Italy

Taxonomy and systematics

The genus Balaenoptera contains the following extant species and subspecies:
Many fossil Balaenoptera species have been described. Some are either nondiagnostic, highly fragmentary, or had no holotype specimen named, hence are considered nomina dubia. The valid fossil species of Balaenoptera are:
  • †Balaenoptera bertae is a relatively small species from the Upper Miocene to Upper Pliocene Purisima Formation of California.
  • †Balaenoptera cephalus was originally thought to be a species of Eschrichtius or Cetotherium, but more recent analysis shows it to be a member of Balaenoptera. Fossils of the species were found in the Calvert Formation of Maryland.
  • †Balaenoptera colcloughi is known from four specimens, including four skulls and some postcranial remains, found at the San Diego Formation. It was a close relative of Megaptera novaeangliae, B. siberi, and B. physalus.
  • †"Balaenoptera" cortesii is a small species based on a juvenile specimen from Montezago; it probably represents a distinct, unnamed genus of balaenopterid.
  • †Balaenoptera davidsonii, like B. cephalus, was originally classified under Eschrichtius, but it has since been moved to Balaenoptera. It was native to the Pliocene San Diego Formation of California. The only known fossil of B. davidsonii is a fragment of the left dentary.
  • †"Balaenoptera" portisi is based on MGPT 13803 from Montafia, and may be the same genus or species as Cetotheriophanes capellinii. The species "B. floridana" is indistinguishable from "B." portisi.
  • †"Balaenoptera" ryani is a valid species but is not in fact a species of Balaenoptera. It probably represents a distinct genus of basal balaenopterid.
  • †Balaenoptera siberi is known from two complete skeletons. Its affinity with the genus Balaenoptera has been questioned.
  • †Balaenoptera sursiplana is a fragmentary species, based on a single fossilized tympanic bone.
  • †Balaenoptera taiwanica is named after Taiwan, where the fossil was found in the Pliocene-aged Cholan Formation. B. taiwanica is also based on a single tympanic bone, which is similar to that of B. physalus, the fin whale.