''Podiceps howardae'' is a possible extinct species of

grebe Grebes () are aquatic diving birds in the order (biology), order Podicipediformes (). Grebes are widely distributed freshwater birds, with some species also found in sea, marine habitats during Bird migration, migration and winter. Most grebes f ...

from the United States, possibly a larger and earlier form of the

horned grebe The horned grebe or Slavonian grebe (''Podiceps auritus'') is a relatively small and Threatened species, threatened species of waterbird in the family Podicipedidae. There are two subspecies, ''P. a. auritus'' (Slavonian grebe), which breed ...

(''P. auritus'').

History

In 2001 an article was published that took account of over 10,000 specimens coming from 112 bird species. The age of these fossils date from the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

to the

Zanclean The Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 ± 0.005 Ma (million years ago) and 3.6 ± 0.005 Ma. It is preceded by the Messinian Age of the Miocene Epoch, and f ...

found at Aurora,

Beaufort County, North Carolina Beaufort County ( ) is a County (United States), county located in the U.S. state of North Carolina. As of the 2020 United States census, 2020 census, the population was 44,652. Its county seat is Washington, North Carolina, Washington. The co ...

, collected from the 1960s to 1970s. The species is named in honor of the paleornithologist Hildegarde Howard for her contribution of fossil birds.

Description

Twenty two bones were used for description by American ornithologist

Robert W. Storer Robert Winthrop Storer (20 September 1914 – 14 December 2008) was an American ornithologist known for his work on avian systematics and evolution, especially of grebes. He was born in Pittsburgh, Pennsylvania. He was the 1997 recipient of the Co ...

. The holotype (

USNM The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...

252314) is a complete right

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

. The femur is similar in proportions to the

, but differs in that the femur of ''P. howardae'' is narrower across the distal end as well as the external

condyle A condyle (;Entry "condyle"
in

being narrow too. Seven other femora were also found and assigned as the paratypes ( KUVP 21240, USNM 177918, USNM 178151, USNM 206413, USNM 215453, USNM 215649, and USNM 460785). A nearly complete

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...

(KUVP 21239) and a proximal half of another one (USNM 250773) is similar in length and width of those found in the largest male horned grebe. The distal portion of the bone from another specimen (USNM 210531), however, shows to be more slender as seen in male and female members of horned grebes. Fragmentary tarsometatarsi, one of a proximal portion (USNM 193175) and the other a distal portion (USNM 206326), are more similar in size to USNM 210531. A nearly complete

coracoid A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...

(USNM 177927) is similar in characteristic to those from horned grebes, but the sternal facet is relatively deeper. A nearly complete

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

(USNM 243764) has a length that is within the range of measurements seen in the humeri of female horned grebes. Additional humeri (a proximal portion USNM 183430 and four distal portions USNM 193242, USNM 215034, USNM 368557, USNM 430524) are within the size range of horned grebe humeri, though a fifth distal (USNM 407798) is much larger and might come from a male bird. The distal portion of an

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

(KUVP 21292) is slightly heavier and wider than the ulnae of horned grebes.

Classification

While Storer (2001) argued that the age and size of the grebe was sufficient to warrant as a new species, Olson and Rasmussen (2001) argued that the material should be transferred over to ''P. auritus'' instead.

Paleobiology

''P. howardae'' comes from the Yorktown Formation dating to the Zanclean. Based on fossils of other birds and fish that have been found there, the area was a coastal environment where various of water and seabirds would have been found there in great abundance.

References

{{Taxonbar, from=Q116033857 howardae Fossil taxa described in 2001 Birds described in 2001