Eudyptula wilsonae n. sp. (1 Viewer)

[Fred Ruhe]

Daniel B. Thomas, Alan J.D. Tennyson, Felix G. Marx, and Daniel T. Ksepka, 2023

Pliocene fossils support a New Zealand origin for the smallest extant penguins

Journal of Paleontology: 1–11
doi:10.1017/jpa.2023.30.

Absract and free pdf: Pliocene fossils support a New Zealand origin for the smallest extant penguins | Journal of Paleontology | Cambridge Core

A late Pliocene (3.36–3.06 Ma) exposure of the Tangahoe Formation on the North Island of New Zealand preserves close fossil relatives of many extant seabird clades. Here, we report an extinct member of the little penguin (Eudyptula Bonaparte, 1856) lineage from the Tangahoe Formation—the smallest extinct crown penguin yet known. Eudyptula wilsonae n. sp. is based on the nearly complete skulls of an adult and a fledged but immature individual. Both skulls show more slender proportions than modern little penguins and precede genome-derived estimates for the divergence between Eudyptula minor minor Forster, 1781 (endemic to New Zealand) and Eudyptula m. novaehollandiae Stephens, 1826 (native to Australia and recently established in New Zealand). This raises the possibility that the fossil taxon represents a lineage directly ancestral to extant little penguins. Our results support a Zealandian origin for little penguins, with subsequent Pleistocene dispersal to Australia and a more recent Holocene range expansion of Eudyptula m. novaehollandiae back into New Zealand.

Enjoy,

Fred

 

[Fred Ruhe]

Systematic paleontology

Aves Linnaeus, 1758 (sensu Gauthier, 1986)
Sphenisciformes Sharpe, 1891 (sensu Clarke et al., 2003)
Spheniscidae Bonaparte, 1831

Eudyptula Bonaparte, 1856

Type species.—Eudyptula minor Forster, 1781.

Eudyptula wilsonae new species

Holotype.—NMNZ S.048854: cranium and upper beak, mandible, and right quadrate of an adult individual

Paratype.—NMNZ S.048855: cranium and upper beak, right lacrimal, and right quadrate of immature individual

Diagnosis.—Differs from extant Eudyptula minor in having more slender skull proportions, including proportionally narrower transverse distances between the caudal margins of the nares, the lateral edges of the salt-gland fossae, and the dorsal rim of the temporal fossae.

Occurrence.—Late Pliocene (Piacenzian) Tangahoe Formation, exposed in the southern Taranaki region of the North Island of New Zealand (Naish et al., 2005). Local Waipipian stage, with exposure constrained to 3.36–3.06 Myr based on oxygen isotope stage and magnetic polarity data (Naish et al., 2005; Raine et al., 2015). Specimens were surface collected as boulders from the base of a nearby exposure of the Tangahoe Formation and do not have an exact location lodged in the Fossil Record Electronic Database (FRED :: The Fossil Record Electronic Database, but see Q21/f0002 for a nearby location).

Etymology.—The species name honors New Zealand ornithologist Kerry-Jayne Wilson, in recognition of her many contributions to seabird conservation, particularly her cofounding of the West Coast Penguin Trust.

Fred



Figure 1. Skull of Eudyptula wilsonae n. sp., specimen NMNZ S.048854, presented alongside a skull from Eudyptula m. minor Forster, 1781, specimen NMNZ S.000863, for comparison. Left lateral view: (1) NMNZ S.048854; (3) NMNZ S.000863. Caudal view: (2) NMNZ S.048854; (4) NMNZ S.000863. Right lateral view: (5) NMNZ S.048854. Dorsal view: (6) NMNZ S.048854; (8) NMNZ S.000863. (7) Detail of nasal region of NMNZ S.048854 identifying fused frontal-nasal suture (compare with specimen NMNZ S.048855 in Fig. 1.2).

Figure 2. Skull of Eudyptula wilsonae n. sp., specimen NMNZ S.048855: (1) left lateral view; (2) cranial view; (3) right lateral view; (4) caudal view; (5) dorsal view. (6) Detail of nasal region of skull identifying unfused sutures between premaxillae and nasals.

Figure 3. Strict consensus of most parsimonious trees. Evolutionary relationships for Eudyptula wilsonae n. sp. described in this study were not fully resolved. Instead, Eudyptula wilsonae n. sp. is placed in a clade with extant and fossil Spheniscus, Inguza predemersus and Madrynornis mirandus. Location information for species in this clade are identified with colored symbols: green = New Zealand; purple = Australia; blue = South America, Falkland Islands, and Galápagos Islands; yellow = South Africa.