Mancallinae
From Wikipedia, the free encyclopedia
| Mancalla Fossil range: Late Miocene - Early Pleistocene |
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Alcodes |
The Mancallinae were a sub-family of prehistoric flightless auks that lived on the Pacific coast of today's California and Mexico from the late Miocene Epoch to the Early Pleistocene. They are sometimes collectively referred to as Lucas auks after the scientist who described the first species, Frederic Augustus Lucas.
They had evolved along somewhat similar lines as the Great Auk, their North Atlantic ecological counterpart, but their decidedly stubbier wings were in some aspects more convergent with penguins.
Compared with the subarctic Great Auk, they were also smaller (see also: Bergmann's Rule): 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.
[edit] Evolution and systematics
- Family Alcidae
- Subfamily Mancallinae
- Genus Alcodes
- Alcodes ulnulus
- Genus Praemancalla
- Praemancalla lagunensis (Howard, 1966)[verification needed]
- Praemancalla wetmorei (Howard, 1976)[verification needed]
- Genus Mancalla
- Mancalla californiensis (Lucas, 1901)[verification needed]
- Mancalla diegense (Miller, 1937)[verification needed]
- Mancalla milleri (Howard, 1970)[verification needed]
- Mancalla cedrosensis (Howard, 1971)[verification needed]
- Mancalla emlongi (Olson, 1981)[verification needed]
- Genus Alcodes
- Subfamily Mancallinae
There seems to exist a further, undescribed species which differs somewhat from the others in the proportion of the wing bones (Livezey, 1988).
The mancallines probably evolved from proto-puffins (Livezey, 1988), which must have been birds not dissimilar to the Rhinoceros Auklet. 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 found in Late Miocene (Clarendonian, 9-12 mya) deposits at Laguna Hills, California. 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 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 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 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)[citation needed], some time after the ecological changes had passed their peak.
[edit] References
- Comins, Niel F. & Kaufmann, William J., III (2005): Discovering the Universe (7th edition). Susan Finnemore Brennan, New York City. ISBN 0-7167-7584-0
- Livezey, Bradley C. (1988): Morphometrics of flightlessness in the Alcidae. Auk 105(4): 681–698. PDF fulltext
- Lucas, F. A. (1901): A flightless auk, Mancalla californiensis, from the Miocene of California. Proceedings of the U.S. National Museum 24: 133-134.
- Olson, Storrs L. (1985): The fossil record of birds. In: Farner, D.S.; King, J.R. & Parkes, Kenneth C. (eds.): Avian Biology 8: 79-238. Academic Press, New York.
