This week's 'missing' transitional fossil is a new species of baleen whale which lived in what is now the North Pacific, 30 - 33 million years ago. It shows distinct evidence of transition between the toothed and the baleen whales.
Fucaia buelli is described in a paper published today in Royal Society Open Science by Ewan Fordyce and Cheng-Hsiu Tsa of the University of Otago, New Zealand and Dr Felix Marx of Museum Victoria, Melbourne, Victoria, Australia.
Archaic toothed mysticetes represent the evolutionary transition from raptorial to bulk filter feeding in baleen whales. Aetiocetids, in particular, preserve an intermediate morphological stage in which teeth functioned alongside a precursor of baleen, the hallmark of all modern mysticetes. To date, however, aetiocetids are almost exclusively Late Oligocene and coeval with both other toothed mysticetes and fully fledged filter feeders. By contrast, reports of cetaceans from the Early Oligocene remain rare, leaving the origins of aetiocetids, and thus of baleen, largely in the dark. Here, we report a new aetiocetid, Fucaia buelli, from the earliest Oligocene (ca 33–31 Ma) of western North America. The new material narrows the temporal gap between aetiocetids and the oldest known mysticete, Llanocetus (ca 34 Ma). The specimen preserves abundant morphological detail relating to the phylogenetically informative ear bones (otherwise poorly documented in this family), the hyoid apparatus and much of the (heterodont) dentition. Fucaia comprises some of the smallest known mysticetes, comparable in size with the smallest odontocetes. Based on their phylogenetic relationships and dental and mandibular morphology, including tooth wear patterns, we propose that aetiocetids were suction-assisted raptorial feeders and interpret this strategy as a crucial, intermediary step, enabling the transition from raptorial to filter feeding. Following this line of argument, a combination of raptorial and suction feeding would have been ancestral to all toothed mysticetes, and possibly even baleen whales as a whole.*
A new Early Oligocene toothed ‘baleen’ whale (Mysticeti: Aetiocetidae) from western North America: one of the oldest and the smallest
Felix G. Marx, Cheng-Hsiu Tsai, R. Ewan Fordyce
R. Soc. open sci. 2015 2 150476; DOI: 10.1098/rsos.150476. Published 2 December 2015
*Copyright The Authors. Reprinted under terms of Creative Commons Licence (CC-BY 4.0)
The significance of this find is that it may answer one of the remaining mysteries in mammalian evolution - how did the baleen whales, the Mysticeti sub-order, evolve out of the toothed whales? Like all fossils, it is, of course, transitional, since it represents a snapshot of the evolution of that particular species at that point in time. However, what makes this an outstanding example of transition is that it is from a point close to the divergence of the whales into the two major branches, the toothed and the baleen whales.
Toothed whales like dolphins and orcas have the more normal teeth of their land-based ancestors, while the baleen whales use plates of baleen to filter feed on small prey which is taken in in a large gulp of water which is then forced out of the mouth through the baleen filter. The belief is that this evolved as an ancestor like Fucaia buelli began to feed on shoals of small fish. Fucaia buelli is the oldest baleen whale known and also one of the smallest. Most toothed whales are small compared to the very large baleen whales such as the blue whale.
Like all transitional fossils, the Creation industry is now going to have to work overtime to find reasons to explain it away and think up ways to mislead people about it, rather than admit that these transitional forms actually exist, and exist in abundance throughout the fossil record.
'via Blog this'