Seabirds from the Pleistocene of Japan (1 Viewer)

Watanabe, J., A. Koizumi, R. Nakagawa, K. Takahashi, T. Tanaka, and H. Matsuoka (2020)
Seabirds (Aves) from the Pleistocene Kazusa and Shimosa groups, central Japan
Journal of Vertebrate Paleontology (advance online publication)
doi: 10.1080/02724634.2019.1697277
https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1697277

Although the North Pacific has been a key area for investigations into seabird ecology and evolution, the seabird fossil record has been scarce on the western North Pacific. This study describes new seabird remains from the Pleistocene Kazusa and Shimosa groups, central Honshu Island, Japan, adding new insight into the Pleistocene seabird fauna in the region. Avian materials from four formations (the Hirayama, Ichijiku, and Mandano formations in the Kazusa Group and the Kiyokawa Formation in the Shimosa Group) include at least nine species of seabirds and other waterbirds: Melanitta fusca, Clangula hyemalis, Anatidae? gen. et sp. indet., Gavia stellata?, Phoebastria cf. albatrus, Puffinus cf. puffinus complex, Phalacrocoracidae gen. et sp. indet., Alle cf. alle, and Mancalla sp. Most of these occurrences represent the oldest records for the respective taxa in the western North Pacific. The occurrence of Alle from the Ichijiku Formation (∼0.7 Ma) is especially noteworthy, because modern Alle alle, the sole recognized member of the genus, is rarely recorded in the Pacific today. This record suggests that in the middle Pleistocene, the taxon was probably more widespread in the North Pacific than it is today. Therefore, the present-day distribution of these seabirds is likely a relict of past ones, as has also been documented in some other seabird lineages.

SYSTEMATIC PALEONTOLOGY

Order ANSERIFORMES Wagler, 1831
Family ANATIDAE Leach, 1820
Subfamily ANATINAE Leach, 1820
Tribe MERGINI Rafinesque, 1815
Genus MELANITTA Boie, 1822
MELANITTA FUSCA (Linnaeus, 1758) sensu Dickinson and Remsen, 2013
Material—KUGM FA 2018.001, proximal left humerus from the Mandano Formation; NSM PV 15443, left humeral shaft from the Kiyokawa Formation.

Genus CLANGULA Leach in Ross, 1819
CLANGULA HYEMALIS (Linnaeus, 1758)
Material—KUGM FA 2018.002, left distal humerus from the Ichijiku Formation

ANATIDAE?, gen. et sp. indet.
Material—KUGM FA 2018.008, proximal fragment of the first phalanx of the right fourth pedal digit from the Hirayama Formation.

Order GAVIIFORMES Wetmore and Miller, 1926
Family GAVIIDAE Allen, 1897 (Gray, 1840)
Genus GAVIA Forster, 1788
GAVIA STELLATA? (Pontoppidan, 1763)
Material—NSM PV 24659, fragmentary right humeral shaft; NSM PV 24651 and NSM PV 24652, fragmentary left humeral shafts. All from the Ichijiku Formation.

Order PROCELLARIIFORMES Fürbringer, 1888
Family DIOMEDEIDAE Gray, 1840
Genus PHOEBASTRIA Reichenbach, 1853
PHOEBASTRIA cf. ALBATRUS (Pallas, 1769)
Material—KUGM FA 2018.007, right humeral shaft from the Hirayama Formation.

Family PROCELLARIIDAE Leach, 1820
Genus PUFFINUS Brisson, 1760
PUFFINUS cf. PUFFINUS (Brünnich, 1764) complex
Material—KUGM FA 2018.005, right distal humerus from the Ichijiku Formation; NSM PV 15442, right proximal humerus from the Kiyokawa Formation.

Order SULIFORMES Sharpe, 1891
Family PHALACROCORACIDAE Reichenbach, 1853 (1836)
PHALACROCORACIDAE, gen. et sp. indet.
Material—NSM PV 24653, right humeral shaft from the Ichijiku Formation.

Order CHARADRIIFORMES Huxley, 1867
Family ALCIDAE Rafinesque, 1815
Subfamily ALCINAE Rafinesque, 1815
Genus ALLE Link, 1806
ALLE cf. ALLE (Linnaeus, 1758)
Material—KUGM FA 2018.003, left humerus lacking proximal end from the Ichijiku Formation.

Subfamily MANCALLINAE Miller, 1946
Genus MANCALLA Lucas, 1901
MANCALLA sp.
Material—NSM PV 24658, fragmentary left coracoid; NSM PV 24656 and KUGM FA 2018.004, left and right proximal humeri, respectively; KUGM FA 2018.006, left humerus lacking distal end; NSM PV 24657, left distal humerus. All from the Ichijiku Formation.
The present record from the Ichijiku Formation is the second example from the western North Pacific formally described to date and represents the oldest record in the region (MIS 17).

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