I just found out that birds have "egg teeth". are they the same as in other reptiles?
Hi Russ!
Great question! My hunch is "no." I can envision a crocodilian-bird connection, but not all groups. I would vote that they arose independently.
Perhaps this is a question you could direct to Gunter Wagner and or Jacques Gauthier, both at Yale.
Please check this link for the said query
https://books.google.co.in/books?id=d93wBQAAQBAJ&pg=PA303&lpg=PA303&dq=are+the+egg+teeth+of+birds,+snakes,+turtles+and+crocodilians+homologous&source=bl&ots=wETDiVikib&sig=J-5J_H0NBf5-GJmLisoz8rXtyZE&hl=en&sa=X&ved=0ahUKEwis2NOVjLfNAhXKqo8KHa9RB-MQ6AEIKjAD#v=onepage&q=are%20the%20egg%20teeth%20of%20birds%2C%20snakes%2C%20turtles%20and%20crocodilians%20homologous&f=false
See: See: Ferguson MWJ. Reproductive biology and embryology of the crocodilians. Biology of the Reptilia, Vol 14, Chapter 5, Pages 450-451.
Birds, crocodiles and turtles have an epidermal horn (egg caruncle) whereas snakes and lizards use a true tooth for the same purpose: these are obviously not simply homologous in terms of the tissues involved, but it is possible to interpret them as historically homologous based on an evolutionary/developmental trajectory. Monotremes actually have BOTH a caruncle and a median tooth that are linked by a median mesenchymal strand (Hill & de Beer 1950, DOI: 10.1111/j.1096-3642.1950.tb00226.x) so may be expressions of a common developmental program.
Hair, scales and feathers arose from one ancestral structure, a new study finds.
Studies in fetal Nile crocodiles, bearded dragon lizards and corn snakes appear to have settled a long-standing debate on the rise of skin coverings. Special skin bumps long known to direct the development of hair in mammals and feathers in birds also turn out to signal scale growth in reptiles, implying all three structures evolved from a shared ancestor, scientists report online June 24 in Science Advances.
Check out Science News on my FB
this sentence: "Special skin bumps long known to direct the development of hair in mammals and feathers in birds also turn out to signal scale growth in reptiles" makes no sense whatsoever.
Try instead: "Special skin bumps long known to direct the development of hair in mammals and feathers in birds also turn out to signal scale growth in non-avian reptiles too".
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