''Eobalaenoptera'' is an extinct genus of

baleen whale Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

belonging to Balaenopteroidea.

Discovery and significance

''Eobalaenoptera'' was first described in June 2004 by researchers at the

Virginia Museum of Natural History The Virginia Museum of Natural History is the state's natural history museum located in Martinsville, Virginia founded in 1984. The museum has several different award-winning publications, is affiliated with the Smithsonian Institution, and has ...

from a partial skeleton found in 1990 in

Caroline County, Virginia Caroline County is a United States county located in the eastern part of the Commonwealth of Virginia. The northern boundary of the county borders on the Rappahannock River, notably at the historic town of Port Royal. The Caroline county sea ...

, the site of a prehistoric ocean, in the middle

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Calvert Formation The Calvert Formation is a geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene epoch of the Neogene period. The formation is a destination for amateur fossil hunters as well as pr ...

. The 11 m (35 ft) skeleton proved to have similar morphological characteristics to a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s consisting of two modern taxonomic

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...

–

Balaenopteridae Rorquals () are the largest group of baleen whales, which comprise the family Balaenopteridae, containing ten extant species in three genera. They include the largest animal that has ever lived, the blue whale, which can reach , and the fin wha ...

(the

rorqual Rorquals () are the largest group of baleen whales, which comprise the family Balaenopteridae, containing ten extant species in three genera. They include the largest animal that has ever lived, the blue whale, which can reach , and the fin wha ...

s), and

Eschrichtiidae Eschrichtiidae or the gray whales is a family of baleen whale (Parvorder Mysticeti) with a single extant species, the gray whale (''Eschrichtius robustus''), as well as three described fossil genera: '' Archaeschrichtius'' and ''Eschrichtioide ...

(a family with one surviving species, the

gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bree ...

). The age of the Calvert Formation (14 million years) makes ''Eobalaenoptera'' the oldest known member of Balaenopteroidea by three to five million years. It also considerably narrowed the gap between the earliest known fossil record and estimated time of divergence of this clade from other baleen whales. Molecular clocks have put this divergence for balaenopteroids from other crown mysticetes by 15–20 million years. In their review of extant and fossil rorquals, Demere et al. (2005) questioned the balaenopteroid placement of ''Eobalaenoptera'', noting that the holotype lack substantial cranial material that could reinforce its original classification, preferring to treat the genus as Chaeomysticeti ''incertae sedis''.T. A. Demere, A. Berta, and M. R. McGowen. 2005. The taxonomic and evolutionary history of modern balaenopteroid mysticetes. Journal of Mammalian Evolution 12(1/2):99-143.

Etymology

The genus name ''Eobalaenoptera'' reflects the similarities between this skeleton and species in the genus ''Balaenoptera'' such as the

minke whale The minke whale (), or lesser rorqual, is a species complex of baleen whale. The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale. The minke whale was first described by the Danish n ...

; ''eo-'' is a prefix meaning dawn. The species is named after Carter Harrison, a volunteer worker at the museum.

References

* Baleen whales Miocene cetaceans Prehistoric cetacean genera Fossil taxa described in 2004 Miocene mammals of North America {{Paleo-whale-stub