05 January 2010

Ancient toothed whale shows Charles Darwin was right

Mammalodon colliveri was a 3 m long animal who lived 25 million years ago. New research by Eric Fitzgerald, a paleobiologist from the Victoria Museum in Melbourne (Australia), revealed that this ancestor of a baleen whale still had teeth and it had not yet evolved the baleen plates.

According to Fitzgerald, it was a bottom-feeding mud-sucker that may have used its tongue and short snout to suck small prey from sand and mud on the seafloor.

Charles Darwin's, in his book ‘On the Origin of Species’, speculated that some of the earliest baleen whales may have been suction feeders and that their mud grubbing served as a precursor to the filter feeding of the modern mysticetes. This was back in 1859. And as usual, Darwin was perfectly right.

Silvia Bonizzoni

Painting by Brian Choo (Museum Victoria, Melbourne, Australia)

For more information:

Fitzgerald E.M.G. 2010. The morphology and systematics of Mammalodon colliveri (Cetacea: Mysticeti), a toothed mysticete from the Oligocene of Australia. Zoological Journal of the Linnean Society. DOI: 10.1111/j.1096-3642.2009.00572.x

ABSTRACT - Mammalodon colliveri is an unusual toothed archaic mysticete (Cetacea) from the Upper Oligocene Jan Juc Formation of south-east Australia. The morphology of the holotype skull and postcrania are described in detail. Superimposed on the generally plesiomorphic archaeocete-like morphology of Mammalodon are subtle mysticete synapomorphies. Derived features of Mammalodon include a short and bluntly rounded rostrum, reduced premaxillae, and anterodorsally directed orbits. Within Mysticeti, this suite of features is unique. The aberrant rostral morphology of Mammalodon suggests specialization for suction feeding. Janjucetus hunderi is placed in an expanded family Mammalodontidae. Phylogenetic analysis corroborates the monophyly of Basilosauridae, Neoceti, Odontoceti, and Mysticeti, and yields a novel hypothesis of toothed mysticete relationships: a basal clade of undescribed toothed mysticetes from South Carolina, a Llanocetidae + Mammalodontidae clade, and monophyletic Aetiocetidae are posited as successive sister taxa to edentulous baleen whales (Chaeomysticeti). Toothed archaic mysticetes clearly employed diverse prey capture strategies, with exaptations for filter feeding evolving sequentially in stem group Mysticeti. A stratigraphically calibrated phylogeny implies that the initial diversification of Mysticeti occurred during the Late Eocene.

1 comment:

if borsani said...

mi puoi mandare il pdf? grazie se si ma anche se no... buon anno juniofabrizio.borsani@isprambiente.it