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RE: Paleontology and Dinosaurology 101: What layperson MUST to know about?



> -----Original Message-----
> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Renato Santos
> Sent: Monday, February 07, 2011 7:18 AM
> To: dinosaur@usc.edu
> Subject: Re: Paleontology and Dinosaurology 101: What 
> layperson MUST to know about?
> 
> Dr Holtz,
> 
> Great post but if I may be so bold as to point out the 
> imprecision in this:
> > * While most of the coal swamp plants reproduced by means 
> of spores, 
> > one branch evolved a method of reproduction using a seed.
> Spermatophytes still reproduce by means of spores, pollen and
> macrospores: a seed has a greater analogy to an amniote egg.

True enough: this was obviously simplified.

> Also
> > * Early terrestrial vertebrates were often competent at 
> moving around 
> > on land as adults, but typically had to go back to the 
> water in order 
> > to reproduce. In the coal swamps one branch of these 
> animals evolved a 
> > specialized egg that allowed them to reproduce on land, and 
> thus avoid 
> > the tadpole stage.
> I was under the impression that the tadpole stage was a 
> specialization of Anura+Caudata...

Juvenile semouryiamorphs, temnospondyls, and others have external gills and 
were fully aquatic: "tadpoles" in the broad sense.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA