Penguins, Sphenisciformes, first appeared in the Palaeocene of New Zealand, and subsequently spread around the Southern Hemisphere, reaching Antarctica, South America, Africa, and the Galapagos Islands. While typically associated with cool climates today, Penguins probably reached their most diverse during the warm greenhouse climates of the Oligocene and Eocene, when a number of giant species (species significantly larger than modern Emperor Penguins, Aptenodytes forsteri) are known from New Zealand and Antarctica.
In a paper published in the journal Nature Communications on 12 December 2017, Gerald Mayr of the Ornithological Section at the Senckenberg Research Institute and Natural History Museum Frankfurt, Paul Scofield and Vanesa De Pietri of the Canterbury Museum, and Alan Tennyson of the Museum of New Zealand Te Papa Tongarewa, describe a new species of Giant Penguin from the Late Palaeocene of Hampden Beach in Otago, South Island.
The new species is named Kumimanu biceae, where 'Kumimanu' means 'Monster Bird' in Maori and 'biceae' honours Alan Tennyson's mother, Beatrice ('Bice') Tennyson. It is described from a partial skeleton comprising a partial left scapula, an incomplete right coracoid, part of the sternum, a partial left humerus, an incomplete left ulna, the right femur, most of the right tibiotarsus, a partial synsacrum, three vertebrae, and various bone fragments. From these it is estimated to have had a body length of about 1.77 m, and a mass of about 101 kg.
Wing and pectoral girdle bones of the new Giant Penguin, Kumimanu biceae. (a) Whole specimen, partially prepared concretion with all bones in situ. (b) Right coracoid in dorsal view (dotted lines indicate reconstructed outline of bone). (c) Left coracoid of Waimanu tuatahi from the late Paleocene of New Zealand. (d)–(f) Fragmentary proximal end of the left ulna of Kumimanu biceae in (d) dorsal, (e) ventral, and (f) proximal view. (g), (h) Left ulna of an undescribed new Sphenisciform from the Waipara Greensand in (g) ventral and (h) proximal view; the dashed line in (g) indicates the portion of the bone preserved in the Kumimanu biceae. (i) CT image of cranial surface of partial left humerus. (j) Exposed caudal surface of the bone, surrounding bones and matrix were digitally brightened. (k), (l) CT images of caudal humerus surface with (k) minimum and (l) maximum length estimates based on the reconstructed outline of the bone (dotted lines). (m) Left humerus of Crossvallia unienwillia from the late Paleocene of Antarctica, which is one of the largest previously known Paleocene Penguin species. (n) Left humerus of Pachydyptes ponderous from the late Eocene of New Zealand, which was previously considered one of the largest fossil penguins. Abbreviations: cor, coracoid; dcp, dorsal cotylar process; fem, femur; fpt, fossa pneumotricipitalis; hum, humerus; olc, olecranon; ppc, procoracoid process; scc, scapular cotyla; sup, attachment scar for supracoracoideus muscle; tbt, tibiotarsus; vct, ventral cotyla. Scale bars equal 50 mm; same scale for (b) and (c), (f) and (h), and (i)-(l), respectively. Mayr ey al. (2017).
A phylogenetic analysis suggests that Kumimanu biceae is not closely related to the Giant Penguins of the Oligocene and Eocene, but represents a separate evolutionary lineage that arose from smaller ancestors. Mayr et al. note that the appearance of such a large Penguin so shortly after the End Cretaceous Extinction is significant, and that this may imply Penguins reached large sizes not in response to the warm climate of the Oligocene and Eocene, but rather the sudden absence of large Marine Reptiles, creating an evolutionary niche that few other groups were ready to exploit. They further observe that the disappearance of these large forms by the end of the Eocene may, therefore, not by due to the cooling climate of the time, but rather the appearance of Marine Mammals such as Toothed Whales and Seals, which would have occupied a similar ecological niche to the Giant Penguins, and in the case of Seals, competed with them directly for coastal breeding grounds.
Further bones of Kumimanu biceae. (a) Cranial portion of left scapula; in (b) the surrounding matrix and bones were digitally removed; the dotted line demarks an overlying bone fragment. (c) Left scapula of Waimanu tuatahi from the late Paleocene of New Zealand. (d), (e) Thoracic vertebra of Kumimanu biceae in (d) caudal and (e) right lateral view. (f) Right femur of Kumimanu biceae in craniomedial view. (g) Kumimanu biceae, sternum in cranial view. (h) Right tibiotarsus in cranial view. (i) Digitally reconstructed distal end of tibiotarsus, in which the medial condyle was brought into its presumed original position and a piece of adhering bone fragment and matrix were removed. (j) Distal end of right tibiotarsus of Waimanu manneringi. Abbreviations: afh, articulation facet of humerus; cas, coracoidal articulation sulcus; cdf, caudal articulation facet; crf, cranial articulation facet; ext, extensor sulcus; fem, femur; fib, fibular crest; lcd, lateral condyle; mcd, medial condyle; stk, sternal keel; vtp, ventral process. Scale bars equal 50mm. Mayr ey al. (2017).
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