PZ Myers. 2004 Dec 02. TWO terrible pterosaur tragedies…. <http://pharyngula.org/index/weblog/two_terrible_pterosaur_tragedies/>. Accessed 2008 Dec 01.

Posted on M00o93H7pQ09L8X1t49cHY01Z5j4TT91fGfr on Thursday, December 02, 2004

TWO terrible pterosaur tragedies…

…or two bits of good news for us. This week's Nature has back-to-back articles on the discovery of two new fossilized pterosaur embryos, one in China and the other in Argentina.

The Chinese fossil hasn't been assigned to a specific species, but the authors compare it to another pteradactyloid, Beipiaopterus. It's from the early Cretaceous, about 120 million years ago, and its parents were living along the shores of a shallow freshwater lake. There is sufficient detail to be able to tell that it's shell was thin and leathery, and not calcareous like a chicken egg.

Early Cretaceous pterosaur egg and embryo (JZMP-03-03-2) from the Yixian Formation of Liaoning, China. Scale bar, 1 cm. Inset, magnification of egg boundary (130%) showing the thin, soft shell and no evidence of lamination structures.

Drawing of the pterosaur egg with embryo. Abbreviations: dv, dorsal vertebrae; fe, femur; hu, humerus; il, ilium; pt, pteroid; pu, pubic; ra, radius; sk, skull outline; t, tooth; ti, tibia; ul, ulna; wm, wing metacarpal; wp, wing phalanges.

The second fossil embryo has a similar story to tell. It's about 100 million years old, and is probably an embryonic Pterodaustro guinazui. This creature also lived in shallow waters, and had a long snout lined with thin filaments for filter feeding—it was a kind of flamingo of the Cretaceous. The details show that it too had a thin leathery eggshell.

Shell around a pterosaurian embryo from the Early Cretaceous period in Argentina (specimen MHIN-UNSL-GEO-V 246). a,b, Scanning electron micrographs of radial sections of the eggshell: note the nucleation centres and bladed crystals at the apex of the V-shaped eggshell units, and micrometre-sized vesicles (ghost protein) on the surfaces. c, Detail showing the eggshell and general preservation of the bones. Abbreviations: bc, bladed crystals; hum, humerus; mcIV, metacarpal IV; nc, eggshell nucleation centres; sh, eggshell; ves, vesicles.

Composite drawing of a pterosaurian embryo from the Early Cretaceous period in Argentina (specimen MHIN-UNSL-GEO-V 246). Abbreviations: bc, bladed crystals; co, coracoid; dv, dorsal vertebrae; fe, femur; ga, gastralia; hu, humerus; mc, metacarpal I–III; mcIV, metacarpal IV; mt, metatarsals I–IV; nc, eggshell nucleation centres; pm, premaxilla; ph1d4, first phalanx of wingfinger; ra, radius; sc, scapula; sk, skull; sh, eggshell; sv, sacral vertebrae; t, tarsals; ti, tibia; ul, ulna; ves, vesicles.

Chiappe LM, Codorniu L, Grellet-Tinner G, Rivarola D (2004) Argentinian unhatched pterosaur fossil. Nature 432:571-572.

Ji Q, Ji S-a, Cheng Y-n, You H-l, Lu J-c, Liu Y-q, Yuan C-x (2004) Pterosaur egg with a leathery shell. Nature 432:572.

1. There has been this character by the name of Dave Peters who claims that pterosaurs were viviparous, among many other crazy theories. I met him about a year ago and he seems to be a brilliant scientist, but he seems horribly misguided by his methods (using Photoshop to trace photos of specimens). He has said that the egg found earlier this year in China was really an egg-eating anurognathid that somehow got preserved inside a dinosaur egg. I'm interested in what he hs to say about these new specimens.
   
   Here is his website: http://www.pterosaurinfo.com/
   #: Posted by Archosaurian  on  12/02  at  09:51 PM
2. Peters has now accepted the earlier find as a genuine embryo. In this post to the Dinosaur Mailing List, in re the new Nature articles, he backpedals but valiantly tries to salvage some of his theory. This post and its follow-up are also interesting.
   #: Posted by  on  12/03  at  11:42 PM
3. Extraordinary blog.
   #: Posted by  on  12/04  at  07:24 AM