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| [upper] Aldiomedes angustirostris Mayr & Tennyson, 2019
[lower] extant Black‐footed Albatross Phoebastria nigripes
DOI: 10.1111/ibi.12757
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Abstract
We describe a nearly complete, three‐dimensionally preserved skull of a new albatross species from the late Pliocene (3.0–3.4 million years ago) Tangahoe Formation of New Zealand. Aldiomedes angustirostris, n. gen. et sp. has only about 90% of the length of the skull of the smallest extant albatross and is the geologically youngest record of a small‐sized albatross known to date. The new species is characterized by a mediolaterally compressed beak, which is not found in any living albatross. The small size and some cranial features of A. angustirostris indicate that, in spite of its comparatively young geological age, the new species was not part of crown group Diomedeidae. We hypothesize that A. angustirostris was more piscivorous than extant albatrosses, which predominantly feed on squid. The reasons for the extinction of smaller‐sized albatrosses are elusive but may be related to changes in seabird fauna during the Pliocene epoch, which witnessed the radiation of various non‐procellariiform seabird groups.
Keywords: Aldiomedes angustirostris, n. gen. et sp., Aves, evolution, palaeoecology
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| Skull of Aldiomedes angustirostris, n. gen. et sp. from the late Pliocene of South Taranaki, New Zealand (holotype, NMNZ S.046313) |
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| Skull of Aldiomedes angustirostris, n. gen. et sp. [upper] from the late Pliocene of South Taranaki, New Zealand (holotype, NMNZ S.046313), in comparison with extant Black‐footed Albatross Phoebastria nigripes [lower].
Scale bars: 1 cm.
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| Figure 2: Skull of Aldiomedes angustirostris, n. gen. et sp. from the late Pliocene of South Taranaki, New Zealand (holotype, NMNZ S.046313), in comparison with extant Diomedeidae (a, c, e, g: dorsal view; b, d, f, h: lateral view). (a, b, d) A. angustirostris; in (d), the neurocranium was digitally brought into its presumed natural position. (c, h) Black‐browed Albatross Thalassarche melanophris. (e) Laysan Albatross Phoebastria immutabilis. (f,g) Black‐footed Albatross Phoebastria nigripes. Scale bars: 10 mm. |
Aves Linnaeus, 1758
Procellariiformes Fürbringer, 1888
Diomedeidae Gray, 1840
Aldiomedes, n. gen.
Aldiomedes angustirostris, n. sp.
Differential diagnosis: Small‐sized albatross, which differs from all extant Diomedeidae (Phoebetria, Phoebastria, Thalassarche and Diomedea) in: smaller size (Table 1), beak mediolaterally narrower and culmen more ridge‐like, nostrils proportionally larger and with slit‐like caudal margin, fossae glandularum nasales narrower, processus paroccipitales more caudally directed, fossae temporales deeper, and crista nuchalis transversa more sharply defined.
Etymology: The taxon is named in honour of Alastair (‘Al’) Johnson, who found the holotype of the new species; the second part of the name refers to Diomedes, the Greek mythological figure, after which the albatross family was named.
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| Skull of Aldiomedes angustirostris, n. gen. et sp. from the late Pliocene of South Taranaki, New Zealand (holotype, NMNZ S.046313) |
Aldiomedes angustirostris, n. sp.
Etymology :The species epithet is derived from angustus (Lat.): narrow and rostrum (Lat.): beak and refers to the unusually narrow beak of the new species.
Gerald Mayr and Alan J. D. Tennyson. 2019. A Small, Narrow‐beaked Albatross from the Pliocene of New Zealand demonstrates A Higher Past Diversity in the Feeding Ecology of the Diomedeidae. Ibis. DOI: 10.1111/ibi.12757
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