Mancalla Californiensis

Mancallinae is an extinct subfamily of prehistoric flightless alcids that lived on the Pacific coast of today's California and Mexico from the late Miocene epoch to the early Pleistocene (ranging from at least 7.4 million to 470,000 years ago). They are sometimes collectively referred to as Lucas auks after the scientist who described the first species, Frederic Augustus Lucas.

Description

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. The last species thus stood around 55–60 cm high in life. The largest species, ''Miomancalla howardi'', was the largest charadriiforme of all time.Smith, N. 2015. Evolution of body mass in the Pan-Alcidae (Aves, Charadriiformes): the effects of combining neontological and paleontological data. Paleobiology. doi: 10.1017/pab.2015.24

Evolution and classification

In a 2011 paper, N. Adam Smith published a review and revision of the Mancallinae. Smith defined Mancallinae as the clade containing ''Mancalla'', ''Miomancalla'', their common ancestor and all its descendants. A summary of his results follows.

*Pan-Alcidae Smith, 2011
**Mancallinae L.Miller, 1946
***'' 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 auks.
*''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- puffins, 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. From the bone's measurements, it seems probable that this species was flightless 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 evolved from one of the two 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.

As with many marine birds, the mancalline auks were much affected by the extinction crisis in the late Pliocene oceans. This coincided with the diversification of marine mammals, but may ultimately have been caused by increased supernova activity in the vicinity of the solar system. 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.

References

{{Taxonbar, from=Q3285302

Auks
Extinct flightless birds
Neogene birds
Bird subfamilies