Mancallinae
Encyclopedia
The Mancallinae were a sub-family of prehistoric flightless auk
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

 relatives that lived on the Pacific coast of today's California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 from the late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 epoch to the early Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 (ranging from at least 7.4 million to 470 thousand years ago). They are sometimes collectively referred to as Lucas auks after the scientist who described the first species, Frederic Augustus Lucas
Frederic Augustus Lucas
Frederic Augustus Lucas, Sc.D. was an American museum director.-Early years:Frederic A. Lucas was born March 25, 1852 at Plymouth, Massachusetts.-Career:...

.

They had evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 along somewhat similar lines as the Great Auk
Great Auk
The Great Auk, Pinguinus impennis, formerly of the genus Alca, was a large, flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus, a group of birds that formerly included one other species of flightless giant auk from the Atlantic Ocean...

, their North Atlantic ecological
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

 counterpart, but their decidedly stubbier wings were in some aspects more convergent
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 with penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...

s.

Compared with the subarctic
Subarctic
The Subarctic is a region in the Northern Hemisphere immediately south of the true Arctic and covering much of Alaska, Canada, the north of Scandinavia, Siberia, and northern Mongolia...

 Great Auk, they were also smaller (see also: Bergmann's Rule
Bergmann's Rule
Bergmann's rule is an ecogeographic principle that states that within a broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been...

): Praemancalla species have been estimated to have weighed about 3 kg. Most Mancalla forms weighed somewhat less (about 2.4 kg), with M. milleri being a smaller (1.65 kg) and M. emlongi a much larger bird (3.8 kg) than the rest (Livezey, 1988). The last species thus stood around 55-60 cm high in life.

Evolution and classification

In a 2011 paper, N. Adam Smith published a review and revision of the Mancallinae. Smith defined Mancallinae as the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 containing Mancalla, Miomancalla, their common ancestor and all its descendants. A summary of his results follows.
  • Pan-Alcidae Smith, 2011
    • Mancallinae Lucas, 1901
      • Mancalla Lucas, 1901
        • Mancalla californiensis Lucas, 1901
        • Mancalla cedrosensis Howard, 1971
        • Mancalla lucasi Smith, 2011
        • Mancalla vegrandis Smith, 2011
      • Miomancalla Smith, 2011
        • Miomancalla howardi (Smith, 2011)
        • Miomancalla wetmorei (Howard, 1976)

The following species could not be identified as unquestionable mancallines, and have been assigned to Pan-Alcidae incertae sedis. They may be mancallines, or more closely related to true auk
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

s.
  • Alcodes ulnulus Howard, 1968
  • Mancalla diegensis Miller, 1937
  • Mancalla milleri Howard, 1970

The following species could not be differentiated from other recognized species of mancallines (see above), and have been assigned to Mancallinae incertae sedis.
  • Mancalla emlongi Olson, 1981
  • Praemancalla lagunensis Howard, 1966

The mancallines probably evolved from proto-puffin
Puffin
Puffins are any of three small species of auk in the bird genus Fratercula with a brightly coloured beak during the breeding season. These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among...

s (Livezey, 1988), which must have been birds not dissimilar to the Rhinoceros Auklet
Rhinoceros Auklet
The Rhinoceros Auklet is a seabird and a close relative of the puffins. It is the only living species of the genus Cerorhinca. Given its close relationship with the puffins, the common name Rhinoceros Puffin has been proposed for the species.It ranges widely across the North Pacific, feeding on...

. Accordingly, their status as a subfamily has been questioned as this would make the Alcinae (true auks) paraphyletic. However, the mancallines were a very distinct and unique evolutionary lineage and are thus usually retained as a subfamily. They must have diverged from flying ancestors during the mid-Miocene, roughly 15 mya.

Alcodes is known from a single ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...

 found in Late Miocene (Clarendonian
Clarendonian
The Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 13,600,000 to 10,300,000 years BP, a period of . It is usually considered to overlap the Serravallian of the Middle...

, 9-12 mya) deposits at Laguna Hills, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. While assignment of such a fragmentary fossil is always problematical, the ulna is a fairly distinctive bone and that of Alcodes is quite peculiar. However, it is more allied with the Mancallines as a matter of convenience; additional material would be needed to confirm this relationship (Olson, 1985). From the bone's measurements, it seems probable that this species was flightless (Livezey, 1988) and judging from its age, it either represents an earlier development parallelling Mancalla, or a third lineage of flightless auks.

Praemancalla is known from Clarendonian to Early Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 remains. It is similar to Mancalla, but less extreme in its adaptations and it is quite possibly that the latter genus evolved from one of the 2 known species. Mancalla was a common species throughout the Pliocene, appearing in the Hemphillian
Hemphillian
The Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 10,300,000 to 4,900,000 years BP, a period of . It is usually considered to overlap the Tortonian epoch of the Late...

 stage of the Late Miocene (5-9 mya), and spreading in the Pliocene, with 4 species apparently coexisting at one time on the coast of southern California (Olson, 1985).

As with many marine birds, the mancalline auks were much affected by the extinction crisis in the late Pliocene oceans. This cocincided with the diversification of marine mammals, but may ultimately have been caused by increased supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

activity in the vicinity of the solar system (Comins & Kaufmann). Despite their apparent awkwardness, they seem to have been quite well adapted for flightless birds, with the fossil record suggesting that the last remnants did not disappear until the Early Pleistocene (c. 7 mya), some time after the ecological changes had passed their peak.
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