[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Ankle Articulation in Pterosaurs



A while back I posed a question about pterosaur characteristics that
separate them cladistically from dinosaurs. I was temporarily out of touch
with the list because of server updates, so I may have missed some of the
responses. I did receive Jay Freeman's post about the vertebrate zoology
exam that asked "Which of these animals would be most suitable for a
Hallowe'en costume: brachiosaur, Pteranodon, T. rex, Triceratops,
plesiosaur, or Dimetrodon. The accepted answer, Jay relates, was "T. rex"
because "They walked like men." A check in the archives indicated there
were no other responses.

In Wellnhofer's _Illustrated Encyclopedia of Pterosaurs_, however, there
is a paragraph about ankle/foot articulation with the statement "...the
ankle could allow right-angled articulation of the foot with the tibia.
This is an indication of a plantigrade position of the foot (i.e., with
the sole on the ground) when walking. Thus pterosaurs were not digitigrade
like birds--walking on the toes--but plantigrade--walking on the soles of
the feet--like man." (Wellnhofer, p. 57)

Would this "digitigrade position of the foot" be a dinosaur/bird trait
that would be useful in explaining to laypeople (myself included) why
pterosaurs cannot be included among the dinosaurs? (I don't want to use
the "dinosaurs lived only on the land and could not fly" rationale because
I want to leave open the option of including birds among the dinosaurs.)

----- Amado Narvaez
      Media Specialist
      Montgomery Knolls ES
      807 Daleview Drive
      Silver Spring, MD 20901