RE: Janjucetus hunderi (RE: Ancient Whale Broke all the Rules)

["Choo, Brian" <bchoo@museum.vic.gov.au>]

David Marjanovic = 
> It looks a lot like *Dakosaurus*!

It does in profile - when seen from above it looks more like a
rhomalaeosaurid pliosaur(Dak's snout doesn't taper as much towards a
terminal roseatte).

> But... I thought toothed predatory mysticetes from the Oligocene were 
nothing new? So just the completeness and the huge unmammalian eyes are
new?

Other toothed mysticetes have been described but these forms have been
argued to have been at least partly bulk-feeding with proto-baleen or
possibly even filter-feeding in crab-eater fashion. JJ is the first
mysti to be an unambiguous macrophagous bite & tear predator that was
collecting prey items one-at-a-time - no other mysti has JJ's
premaxillary roseate of recurved teeth and such humungous temporal
musculature.

Mikko Haaramo = 

> Molar teeth look more like those of the crab-eating seal (_Lobodon
carcinophagus_).
http://images.google.fi/images?q=Lobodon
Maybe an early attemp of krill-eating. :)

JJ is closely compared with both the leopard seal and crab-eater seals
in the supplemental data. The crab-eater lacks the well developed
anterior caniniform dentition and extensive temporalis of leopard+JJ.
JJ's molars shear heavily against each other in occlusion and have
noticeable wear facets unlike the interlocking denticles of a crab-eater
seal's.

(ie. JJ probably grabbed and dismembered prey more like a leopard seal -
although it should be noted that leopards eat some krill as well, but
not by filtration). 

It should also be noted that conditions in the Bass Strait during the
Late Oligocene seem to have been warm subtropical (we have the fossils
of parrotfish) - not the best conditions for swarms of krill.


Brian Choo

Vertebrate palaeontologist and illustrator
website = www.geocities.com/ozraptor4
livejournal = http://www.livejournal.com/users/ozraptor4/


-----Original Message-----
From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf
Of David Marjanovic
Sent: Wednesday, 16 August 2006 9:52 PM
To: DML
Subject: Re: Janjucetus hunderi (RE: Ancient Whale Broke all the Rules)

> An exceedingly bizarre animal - it's a baleen (stem-group
> mysticete)whale sans baleen which was trying to rip-off the
> sauropterygia or perhaps Dakosaurus.

It looks a lot like *Dakosaurus*!

But... I thought toothed predatory mysticetes from the Oligocene were 
nothing new? So just the completeness and the huge unmammalian eyes are
new? 
  
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