@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

A new archaic baleen whale Toipahautea waitaki (early Late Oligocene, New Zealand) and the origins of crown Mysticeti

1. Cheng-Hsiu Tsai, R. Ewan Fordyce. A new archaic baleen whale Toipahautea waitaki (early Late Oligocene, New Zealand) and the origins of crown Mysticeti. Royal Society Open Science, 2018; 5 (4): 172453 DOI: 10.1098/rsos.172453

Geological map, excavation site and initial preparation of †Toipahautea waitaki OU 21981. (a) General map and geological horizon of †Toipahautea waitaki OU 21981; (b) excavation site of †Toipahautea waitaki OU 21981 with RE Fordyce as a scale bar (photo ©CH Tsai); (c) initial preparation of †Toipahautea waitaki OU 21981 by A. Grebneff (photo ©RE Fordyce); (d) scene of excavating †Toipahautea waitaki OU 21981 (photo ©RE Fordyce); the arrow marks the level of the typical basal Duntroonian brachiopod shellbed.

A new genus and species of extinct baleen whale ^†Toipahautea waitaki (Late Oligocene, New Zealand) is based on a skull and associated bones, from the lower Kokoamu Greensand, about 27.5 Ma (local upper Whaingaroan Stage, early Chattian). The upper jaw includes a thin, elongate and apparently toothless maxilla, with evidence of arterial supply for baleen. Open sutures with the premaxilla suggest a flexible (kinetic) upper jaw. The blowhole is well forward. The mandible is bowed laterally and slightly dorsally; unlike the Eomysticetidae, there are no mandibular alveoli, and the coronoid process is tapered and curved laterally. Jaw structure is consistent with baleen-assisted gulp-feeding. The age of early Chattian makes ^†Toipahautea a very early, if not the oldest named, toothless and baleen-bearing mysticete, suggesting that the full transition from toothed to baleen-bearing probably occurred in the Early Oligocene. Late Oligocene mysticetes vary considerably in jaw form and kinesis, tooth form and function, and development of baleen, implying a wide range of raptorial, suctorial and filter-feeding behaviour. More study may elucidate the function of jaws, teeth and baleen in terms of opportunist/generalist feeding, as in modern gray whales, versus specialized feeding. We here propose that early mysticetes, when transitioned from toothed to baleen-bearing, were generalists and opportunists instead of specializing in any forms of feeding strategies. In addition, two different phylogenetic analyses placed ^†Toipahauteaeither in a polytomy including crown Mysticeti, or immediately basal to the crown, and above †Eomysticetidae in both cases. Because the ^†Toipahautea waitaki holotype is an immature individual, it may plot more basally in phylogeny than its true position.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev