Skip to main content

Ancient Fish



This story just came out. I am reminded of Spore, and it's really quite interesting to see how small tiny changes here and there are actually quite important. Here's the abstract and last paragraph from the Nature article concerning Tiktaalik.

*****
Abstract: Among the morphological changes that occurred during the 'fish-to-tetrapod' transition was a marked reorganization of the cranial endoskeleton. Details of this transition, including the sequence of character acquisition, have not been evident from the fossil record. Here we describe the braincase, palatoquadrate and branchial skeleton of Tiktaalik roseae, the Late Devonian sarcopterygian fish most closely related to tetrapods. Although retaining a primitive configuration in many respects, the cranial endoskeleton of T. roseae shares derived features with tetrapods such as a large basal articulation and a flat, horizontally oriented entopterygoid. Other features in T. roseae, like the short, straight hyomandibula, show morphology intermediate between the condition observed in more primitive fish and that observed in tetrapods. The combination of characters in T. roseae helps to resolve the relative timing of modifications in the cranial endoskeleton. The sequence of modifications suggests changes in head mobility and intracranial kinesis that have ramifications for the origin of vertebrate terrestriality.

Last paragraph: With appendages able to support the weight of the body, a more consolidated skull, ribs capable of sustaining the trunk under a gravitational load, a respiratory system less reliant on water breathing, a head capable of independent motion, and cranial proportions approaching those of tetrapods, Tiktaalik reveals an important stage in the origin of terrestrial vertebrates5,6. T. roseae probably inhabited the benthos, shallows, and mudflats of freshwater floodplains while supporting itself on a solid substrate. In the Late Devonian, marginal freshwater environments were an important locus of the evolutionary
changes that led to the origin of amphibious lifestyles among tetrapodomorphs.
*****

Comments

Popular posts from this blog

This weekend sucks!

So the Yankees are facing an uphill battle against the Angels. Hope they pull out of this one. The game today was pretty intense. Down 5-0 then went up 6-5 only to be beaten 11-7. Ugh! I don't know, they just lacked the stamina to pull things through today. Then again, I don't fault them. NY has a pretty tense weekend with the bomb alert, and I pray that all will be well. After all, in my heart NYC is still my home. This weekend is Fall Break. Unfortunately for me, the weather is bad so I probably can't go hiking, and then my boss told me Thursday that we have work to do over the weekend. Right now I am busy testing the microwave/rf generators for our quantum dot gate pulsing. We need to make sure that we can maintain the pulse form sent down to the sample with minimal distortion, reflection, attenuation and loss. This is made particularly difficult due to the size of our metal gates (which I made), on the order of 100 nm or less in width and less than 20 nm in thickness. S...

Coffee!