MEGALANCOSAUR WEIRDNESS

["Matthew Troutman" <m_troutman@hotmail.com>]

<<dangn!
with that neck and forelimb megalcosaurs looks an awfully lot like a
pterosaurid, but that tail looks like it could have come from an
entirely different aniaml, as well as that awfully birdy head.>>

The neck is rather similar to certain prolacertiforms, which Dilkes (1998) 
believes _Megalancosaurus_ and other drepanosaurids belong.  This is in 
contrast to the opinions of Evans (1988) and Renesto (1994) who believe that 
_Megalancosaurus_ falls into a sister-group relation to 
Prolacertiformes+Archosauriformes.  The last person to express the 
pterosaur+_Megalancosaurus_ relationship was Milner (1985), who argued that 
_M_.  was similar enough in forelimb and neck structure to be a close 
pterosaur sister group.  Of course, _M_. is not very similar to pterosaurs 
or birds even in forelimb structure besides being proportionally long 
(compared to the hindlimb).  Feduccia (1996; 1999) thinks that _M_. is 
similar to birds in cervical anatomy, but this doesn't hold up when you look 
at basal birds; the same thing holds for comparison to pterosaurs.

Chiappe (1995) notes that numerous 'protobirds' or 'avimorphs' are claimed 
to have 'birdlike' skulls.  He says that this cannot be broken down into a 
proper character.  Basically, anything with a triangular skull can look 
similar to birds.

Drepanosaurids are very very odd.  I think that the perceived birdlike 
similarities are not really that important.  Drepanosaurids converge a great 
deal on phalangeroids, chameleons, and sloths.  All birdlike characters can 
be interpreted in light of these analogies.

Matt Troutman
m_troutman@hotmail.com

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