The developing bird pelvis passes through ancestral dinosaurian conditions (1 Viewer)

[Fred Ruhe]

Christophor T. Griffin. João F. Botelho, Michael Hanson, Matteo Fabbri, Daniel Smith-Paredes, Ryan M. Carney, Mark A. Norell, Shiro Egawa, Stephen M. Gatesy, Timothy B. Rowe, Ruth M. Elsey, Sterling J. Nesbitt & Bhart-Anjan S. Bhullar, 2022

The developing bird pelvis passes through ancestral dinosaurian conditions

Nature: 1–7. doi:10.1038/s41586-022-04982-w

Abstract: The developing bird pelvis passes through ancestral dinosaurian conditions - Nature

Living birds (Aves) have bodies substantially modified from the ancestral reptilian condition. The avian pelvis in particular experienced major changes during the transition from early archosaurs to living birds1,2. This stepwise transformation is well documented by an excellent fossil record2,3,4; however, the ontogenetic alterations that underly it are less well understood. We used embryological imaging techniques to examine the morphogenesis of avian pelvic tissues in three dimensions, allowing direct comparison with the fossil record. Many ancestral dinosaurian features2 (for example, a forward-facing pubis, short ilium and pubic ‘boot’) are transiently present in the early morphogenesis of birds and arrive at their typical ‘avian’ form after transitioning through a prenatal developmental sequence that mirrors the phylogenetic sequence of character acquisition. We demonstrate quantitatively that avian pelvic ontogeny parallels the non-avian dinosaur-to-bird transition and provide evidence for phenotypic covariance within the pelvis that is conserved across Archosauria. The presence of ancestral states in avian embryos may stem from this conserved covariant relationship. In sum, our data provide evidence that the avian pelvis, whose early development has been little studied5,6,7, evolved through terminal addition—a mechanism8,9,10 whereby new apomorphic states are added to the end of a developmental sequence, resulting in expression8,11 of ancestral character states earlier in that sequence. The phenotypic integration we detected suggests a previously unrecognized mechanism for terminal addition and hints that retention of ancestral states in development is common during evolutionary transitions.

Enjoy,

Fred

 

[Ted Y.]

A short resume in English, please.
If possible. I understand each word, but not the message.
I am not from this planet (Paleontology).

 

[njlarsen]

A parallel example: Humans have developed from a species that had a tail. Human embryonal development goes through a stage where there is a tail present but it disappears before we are born. This paper reports that the bird embryo have some features that are more similar to dinosaurs than what is found in the eventual adult bird. (at least that is the take home message I got from this),
Niels

 

[Ted Y.]

A parallel example: Humans have developed from a species that had a tail. Human embryonal development goes through a stage where there is a tail present but it disappears before we are born. This paper reports that the bird embryo have some features that are more similar to dinosaurs than what is found in the eventual adult bird. (at least that is the take home message I got from this),
Niels

Thank you.
Very clear and interesting.