The closest living relatives of crocodiles and alligators are, perhaps surprisingly, birds. Both are archosauriforms, a group of species that originated about 250 million years ago near the beginning of the Triassic period.
  • crandlecan@mander.xyz
    2·
    2 hours ago

    Even if crocodiles somehow had wings, the metabolic difference in power alone would mean they could never fly.

    How did birds and crocodiles become so different? The conventional assumption has been that their common ancestor was more like a crocodile than a bird—but our new research shows the opposite is most likely the truth.

    Scientists thought warm-bloodedness had appeared only in the dinosaur-bird lineage.

    living crocodiles have four-chambered hearts. The only other groups with such hearts are warm-blooded birds and mammals, and there is a functional connection with warm-bloodedness.

    modern crocodiles have a warm-blooded-style heart but produce the low blood-flow rates and pressures we would expect for their cold-blooded nature. This suggests their hearts once evolved for warm-blooded life.

    Reversion to a cold-blooded metabolism may have saved the crocodile lineage from extinction 66 million years ago, when an asteroid ended most dinosaur lineages, except, of course, the birds.