Why (or is "why" wrong) did appendages for tetrapods come before proper "hips" in fish?

More research has been done on * Cryptotora thamicola*, the first “walking fish” found with bone structure – and consequent gait – that approximates that of tetrapods on land[ (Shouldn’t the “cryptocora” not be in italics? That’s how it is in the article.)

[RIGHT]Tetrapod-like pelvic girdle in a walking cavefish
Brooke E. Flammang, Apinun Suvarnaraksha, Julie Markiewicz & Daphne Soares
Scientific Reports 6, Article number: 23711 (2016)

Published online:
24 March 2016

Full article: http://www.nature.com/articles/srep23711#f6

I understand it’s not the missing link in the up from the sea to caveman progression. But just as I was thinking that I read this paragraph:

It is, however, crucial to note that Cryptotora is not an analogous representative of any early tetrapodamorph described to date. Description of the morphological attributes of early tetrapods that were instrumental in the fin to limb transition included the presence of zygapophyses and large neural spines on vertebrae and a pelvic girdle that was firlmly attached to the axial skeleton; Cryptotora convergently evolved these while no other fish has. However, Cryptotora obviously lacks digited appendages, which evolved before the pelvic girdle in the fin-to-limb transition.

Is it by an overwhelming preponderance of empirical evidence that the earlier evolution of digital appendages is the case for that statement, or is it “it has to come first” as an analytical issue in the biomechanics of tetrapod gait?

ETA: the paragraph above has “convergently evolved.” Why the adverb? I.e., is it just a fuller way to say “evolved” in the way most people/me understand “evolution” or does it distinguish one of alternative modes of evolution?

Which makes four queries for this OP:

  1. Is “why” in hed the wrong word? (A hijack, perhaps)
  2. The styling of the Latin name of the fish. (Not so important)
  3. The OP proper
  4. The “convergent” (Also could lead to hijack.)

I got my money’s worth on this one.

No. Both genus and species names should be italicised.

And the genus name should always be capitalised.


One down, three to go. :slight_smile:

The part of the article that you’ve quoted seems to say that the digits of early tetrapods evolved before the pelvis did (these digits would later evolve into fingers/toes) and that Cryptotora does not have digits. “Appendages” I interpret as meaning fins or limbs.

“Convergently” as an adverb just says that the features evolved in a convergent way. There are many examples of convergent evolution, one of the best known being the similar shapes of sharks, dolphins, and ichthyosaurs despite not being closely related to each other and having relatives that look very different.