The ichthyosaurs were marine reptiles which lived slightly before and during the time of the dinosaurs.  They superficially resembled dolphins, but were actually quite different – having side-to-side tail propulsion rather than up-down tail propulsion, and having both front and hind fins rather than just front fins. 

     The earliest fossils of the ichthyosaurs occur in the Olenekian period of the early Triassic.  Nine different genera of ichthyosaurs suddenly appear in the Olenekian,[1] thus indicating that a rapid evolutionary emergence of the ichthyosaurs was quickly followed by their subsequent speciation into a variety of diverse types – both the sudden emergence and the diversification being completed perhaps within 2 to 4 million years.  By comparison, the whales took about 20 million years to adapt completely to marine life, and another 15 million years to diversify into their current forms.  According to Calloway,

 

Even the oldest known ichthyosaurs are completely adapted to marine life and have no close, gross morphological resemblances to any other reptiles… (this) has posed perplexing problems regarding the ancestry, early evolutionary history, and phylogeny of the group.[2]

 

     The ichthyosaurs subsequently inhabited the Mesozoic oceans for another 152 million years until apparently going extinct at the Cenomanian-Turonian boundary of the mid-Cretaceous.[3]  During their long tenure, they diversified into a number of varieties.  Some of them evolved fish-like dorsal fins and tails.[4]  Others evolved stereoscopic vision and specialized teeth.[5]  Hundreds of species have been named and thousands of fossils of have been found.[6]

     There is a report of one primitive-looking ichthyosaur from the Spathian of Japan, which although appearing primitive in some ways, was already advanced enough to be obligatorily aquatic, as its flippers could not move its body around on land.   Motani et al suggested it is an intermediary between terrestrial reptiles and aquatic ichthyosaurs.  However, its age, 240 million years ago, is about 10 million years after the ichthyosaurs first appeared.[7]  As such, it occurs too late to be a directly ancestral missing link, although, like the snakes with legs and the feathered dinosaurs discussed above, perhaps it is a descendent of a missing link.  The existence of an intermediary such as this, among early specimens of a lineage, indicates that the new form truly did evolve – it was not created.  If it were created by an all-wise God, then what is the purpose of the intermediary?  Was the intermediary poorly designed?  Did God fail in the first attempt? 

          The most natural explanation for these data is neither creation nor gradual evolution.  Rather, it is that evolution acted rapidly to bring about a radically new and different form – so rapidly, in fact, that there was not enough time for missing links to accumulate in the fossil record.