Dear Marmam readers
We report this article which describes and interprets the early basal mysticete
Llanocetus from Eocene rocks of Antarctica.
?Fordyce RE, Marx FG 2018. Gigantism precedes filter feeding in baleen whale
evolution. Current Biology DOI: https://doi.org/10.1016/j.cub.2018.04.027.?
Article summary: Baleen whales (Mysticeti) are the largest animals on Earth,
thanks to their ability to filter huge volumes of small prey from seawater.
Mysticetes appeared during the Late Eocene, but evidence of their early
evolution remains both sparse and controversial [1, 2 ], with several models
competing to explain the origin of baleen-based bulk feeding [3-6 ]. Here, we
describe a virtually complete skull of Llanocetus denticrenatus, the
second-oldest (ca. 34 Ma) mysticete known. The new material represents the same
individual as the type and only specimen, a fragmentary mandible. Phylogenetic
analysis groups Llanocetus with the oldest mysticete, Mystacodon selenensis [2
], into the basal family Llanocetidae. Llanocetus is gigantic (body length ca.
8 m) compared to other early mysticetes [7-9 ]. The broad rostrum has sharp,
widely spaced teeth with marked dental abrasion and attrition, suggesting
biting and occlusal shearing. As in extant mysticetes, the palate bears many
sulci, commonly interpreted as osteological correlates of baleen [3 ].
Unexpectedly, these sulci converge on the upper alveoli, suggesting a
peridental blood supply to well-developed gums, rather than to inter-alveolar
racks of baleen. We interpret Llanocetus as a raptorial or suction feeder,
revealing that whales evolved gigantism well before the emergence of filter
feeding. Rather than driving the origin of mysticetes, baleen and filtering
most likely only arose after an initial phase of suction-assisted raptorial
feeding [2, 4, 5 ]. This scenario differs strikingly from that proposed for
odontocetes, whose defining adaptation-echolocation-was present even in their
earliest representatives [10 ]. ?
Regards, felixgm...@gmail.com<mailto:felixgm...@gmail.com> and
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