Curiously, in looking up this quote
"This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail in just the right place and with just the right hydrological design. The evolution of these forms was all the more remarkable because they evolved from nothingthe ancestral terrestrial reptile had no hump on its back or blade on its tail to act as a precursor - Gould.
I find it on
ICR: The Intriguing Ichthyosaur--an Evolutionary Fish Story? where it is (correctly) attributed to
quote:
11. Martill, D. M. 1993. Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany. Kaupia - Darmstdter Beitrge zur Naturgeschichte. 2: 77-97.
While
A New Approach to Earth History mistakenly attributes it to Gould, but also took the effort to investigate the issue in more detail:
quote:
Utatsusaurus and the origin of ichthyosaurs
Ichthyosaurs — the name means ‘fish lizards’ — were reptile inhabitants of the sea, living at the same time as dinosaurs trod the land and pterosaurs glided in the air. They looked rather like modern dolphins. The smallest was around 1 metre, the biggest, Shonisaurus, an amazing 23 metres, both extremes arising early in their evolution. Ichthyosaurs had eyes as big as those of any animal known, with the record going to the 9-metre-long Temnodontosaurus. Its eyes measuring 26 cm across, Temnodontosaurus was also the first ichthyosaur to be discovered, when in 1811 the 12-year-old Mary Anning found remains of its skull and vertebrae on the Dorset coast.
Despite looking like fish, their anatomy shows they were once land-lubbers, for they had two pairs of limbs, with digit-like bones rather than rays or spines in their flippers, and a shoulder girdle connected to the skull. The roof of the skull had a pair of openings called fenestra: a hallmark of reptiles.
Another indication of their terrestrial origin is their lack of gills. Like marine mammals, they had to draw oxygen from the atmosphere. This was why, when an ichthyosaur embryo in the womb uncurled itself in preparation for birth, it instinctively oriented itself so that it passed out of the womb tail first. Only when its head emerged did it need to breathe, at which point it could take its first gulp of oxygen by immediately swimming to the surface.
Amongst the oldest known ichthyosaurs was Utatsusaurus, from the Lower Triassic of Japan. As in terrestrial reptiles, the pelvic girdle was attached to the spine, but no longer robustly enough to support the body’s weight. Another transitional feature were the equal lengths of humerus and femur. In more advanced ichthyosaurs, including the contemporary Chaohusaurus, the humerus was longer than the femur (the front limb larger than the hind limb) whereas in most terrestrial animals the femur was longer. Utatsusaurus was also closer to terrestrial animals in not having a dorsal fin or a tail fluke. On several fronts, the view that ichthyosaurs were former land-dwellers that evolved adaptations for life at sea is well supported.
He goes on to talk about design and miss-atributes the quote:
quote:
Stephen Jay Gould expresses the wonder of it all:
This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail in just the right place and with just the right hydrological design. The evolution of these forms was all the more remarkable because they evolved from nothing the ancestral terrestrial reptile had no hump on its back or blade on its tail to act as a precursor.
In the Cenozoic, sea-going mammals with terrestrial ancestors — dolphins and killer whales — also converged ‘on a dorsal fin and tail in just the right place and with just the right hydrological design’. Did these ‘remarkable’ innovations evolve from nothing? In the mind of a scientist, evolution from nothing should be a scientifically well-founded inference, not a quasi-religious presupposition. Gould’s position is to believe that matter itself is a miracle-worker, the essentially pantheistic view of Epicurus. By contrast, ‘just the right place’ and ‘just the right hydrological design’ point to processes that were not accidental.
Meanwhile wikipedia has this
quote:
Evolution of fins
Ichthyosaurs are ancient reptiles that resembled dolphins. They first appeared about 245 million years ago and disappeared about 90 million years ago.
"This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail in just the right place and with just the right hydrological design. These structures are all the more remarkable because they evolved from nothing the ancestral terrestrial reptile had no hump on its back or blade on its tail to serve as a precursor."[64]
The biologist Stephen Jay Gould said the ichthyosaur was his favorite example of convergent evolution.[65]
64. Martill D.M. (1993). "Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany". Kaupia - Darmstdter Beitrge zur Naturgeschichte, 2 : 77-97.
65. Gould,Stephen Jay (1993 "Bent Out of Shape" in Eight Little Piggies: Reflections in Natural History. Norton, 179—94. ISBN 9780393311396.
SO ... now we have the actual correct reference, AND that Gould used ichthyosaur as an example of convergent evolution ...
So I got a copy of Eight Little Piggies from the library and read the "Bent Out of Shape" chapter, and I can confirm that Gould did NOT make this statement. The closest I could find was (pg 81):
quote:
In considering the convergence of ichthyosaur upon fish, we must marvel most at the location of the fins and paddles -- the machinery of swimming and balancing. The fore and ind paddles are, perhaps, least remarkable, for ancestral structures are clearly present as front and back limbs of terrestrial forebears -- and these can be modified, as whales and dolphins have done, to forms better suited to sculling than for walking. But the dorsal (back) and caudal (tail) fins are boggling in their precision in convergence with analogous structures in fishes. For terrestrial ancestors of ichthyosaurs obviously possessed neither back nor tail fin, and the ichthyosaurs therefore evolved these structures from scratch -- yet they occupy the position and maintain the form, that hydrodynamic engineers deem optimal for propulsion and balance.
Later in the chapter (pg 93) he notes that Louis Dollo "argued that the tailbend arose because the two-lobed caudal fin of ichthyosaurs evolved from a skin-fold along the back (source of the dorsal fin as well), which extended itself in a posterior direction to form the upper lobe of the tailfin and then pushed the vertebral column down to form the lower lobe. ... " -- so there is an evolutionary path to the convergence of form, but not to the way the internal structures are modified to achieve that form. Being a predator the selection pressure to perfect the swimming ability as much as possible from the given parts would certainly push the features to optimum location and form. No surprises.
Enjoy
Edited by RAZD, : sp
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