A toothless dwarf dolphin (Odontoceti: Xenorophidae) points to explosive feeding diversification of modern whales (Neoceti)
A toothless dwarf dolphin (Odontoceti: Xenorophidae) points to explosive feeding diversification of modern whales (Neoceti)
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DOI：
10.1098/rspb.2017.0531
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发表时间：
2017-08-30
影响因子：
4.7
通讯作者：
Geisler, Jonathan H.
中科院分区：
文献类型：
--
作者：
Boessenecker, Robert W.;Fraser, Danielle;Geisler, Jonathan H.
齿鲸（Odontoceti）适合在水下捕捉猎物，并且拥有所有哺乳动物中最衍生的一些觅食专门化，包括失去乳齿（单齿形），高齿数（多齿形），以及失去离散的齿类（同齿形）。许多现存的齿形动物都有短而宽的喙、较少的牙齿、肉质的嘴唇和较大的舌骨——这些都是适应以鱼和鱿鱼为食的吸食。我们报告了一种新的齿齿石化石，来自渐新世（大约）。南卡罗来纳（intermorostrum xenops, genet sp. 11月），具有吮吸进食的适应性：无牙和缩短的喙（短喙）。在喙部有增大的孔表明有增大的嘴唇或可能有触须。系统发育分析坚定地将内morostrum归为xenenorophidae，这是一个早期分化的齿形动物分支，以长鼻子、异齿海豚为代表。齿状体内是齿状鲸类中最早的专性吸吮进食器，这种进食方式在齿状鲸类中独立进化了几次。对吻侧形状的宏观进化趋势的分析表明，在齿鲸进化过程中，围绕最佳吻侧形状的选择趋于稳定，并且在始新世之后出现了摄食形态的大爆发，预示着现代齿鲸摄食行为的多样性。
Toothed whales (Odontoceti) are adapted for catching prey underwater and possess some of the most derived feeding specializations of all mammals, including the loss of milk teeth (monophyodonty), high tooth count (polydonty), and the loss of discrete tooth classes (homodonty). Many extant odontocetes possess some combination of short, broad rostra, reduced tooth counts, fleshy lips, and enlarged hyoid bones-all adaptations for suction feeding upon fishes and squid. We report a new fossil odontocete from the Oligocene (approx. 30 Ma) of South Carolina (Inermorostrum xenops, gen. et sp. nov.) that possesses adaptations for suction feeding: toothlessness and a shortened rostrum (brevirostry). Enlarged foramina on the rostrum suggest the presence of enlarged lips or perhaps vibrissae. Phylogenetic analysis firmly places Inermorostrum within the Xenorophidae, an early diverging odontocete clade typified by long-snouted, heterodont dolphins. Inermorostrum is the earliest obligate suction feeder within the Odontoceti, a feeding mode that independently evolved several times within the clade. Analysis of macroevolutionary trends in rostral shape indicate stabilizing selection around an optimum rostral shape over the course of odontocete evolution, and a postEocene explosion in feeding morphology, heralding the diversity of feeding behaviour among modern Odontoceti.