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Re: Queries



>Now that the Academic year has well and truely in gear and prac classes are
>starting up, I have a couple of queries regards the dino - _Archaeopteryx_
>- bird link.
>
>1) Has an opposable hallux been reported from any dino?

There has been some debate about the amount of opposability of the hallux
in theropod feet.  In neotheropods, and most especially in tetanurines,
metatarsal and digit I are very reduced.  In several tetanurine groups,
this metatarsal is rotated towards the plantar side of the metatarsus.  In
almost no nonavian dinosaur, though, is digit I fully opposable.

>2) Do any dinos have hollow bones or evidence of air sacs?

Many dinosaurs had hollow bones, theropods in particular.  Some theropods
and sauropods have extensive systems of pleurocoels in the vertebrae (ask
Brooks Britt about this - he ought to know something on the subject...).
Theropod longbones are all hollow.

>3) Have carpo-metacarus or tars-metatarsus (fused hand/wrist, foot/ankle)
>been recorded from dinos?

The carpals of several coelurosaur groups show a trend towards fusion,
forming the semilunate carpal block (which is in origin formed of at least
two carpals).  In Avimimus, a true carpometacarpus is formed.

Ceratosaurians, Avimimus, and Elmisauridae all show true tarsometatarsi.
Archaeopteryx itself only shows the beginning of this structure.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.