Both, Darwinism and Lamarckism support the currently held belief that pan-global mass extinction of Dinosaurs was due to environmental change towards the end of Cretaceous era about 65.5 million years back. But the view about specific climatic change accounting for mass extinction of Dinosaurs has been changing from time to time. The earliest view was that ice age caused mass extinction of Dinosaurs. This view was followed by Asteroid attack on earth. Subsequently a volcanic eruption in India was believed to be the cause of pan-global mass extinction of Dinosaurs that materialized over a period of about one million years. A later view emerged that egg- shell thinning led to Dinosaur extinction. The latest view is that Methane gas emission by Dinosaurs led to global warming. A view has been advanced by Fox News that this global warming is to account for mass extinction of Dinosaurs. So we have moved full circle from ice age to global warming.
Dinosaur extinction was accompanied by extinction of Ammonites (Mollusks), Mesosaurs, Plesiosaurs, and many Mammalian groups. No theory of relationship has been advanced to explain this association of facts. No theory has been advanced to explain as to why not the entire global flora and fauna became extinct due to alleged climate change but only selected groups of animals. There is evidence that birds survived extinction events affecting Dinosaurs. Flowering plants were making their early appearance at the time of Dinosaur extinction.
Dinosaurs first appeared about 230 million years back and were dominant life forms on earth from 200 million years BC (Jurassic era) to 65.5 million years BC (end of Cretaceous). Therefore Dinosaurs had been dominant life forms on earth for 135 million years from beginning of Jurassic era to end of Cretaceous.
Dinosaurs had been present on each and every continent and occupied all habitats. 500 genera and 1000 species of Non-avian Dinosaurs are known as extant species on the basis of fossil remains. Non-avian Dinosaurs ranged in size from present-day birds (e.g. Pigeon) to the size of Sauropods i.e. 60 meters in length and several stories high. Anchiomis is the smallest known Dinosaur with skeletal length of 35 cm and weight of 110 gms.
Dinosaurs shared several traits with birds such as egg-laying, nest-building and inhabiting all available habitats.
The following excerpt from Wikipedia ( http://en.wikipedia.org/wiki/Dinosaur ) shows that Dinosaur extinction was not a sudden event lasting only a few hours, days or years. Rather it was spread over a period of at least one million years.
Possible Paleocene survivors
Main article: Paleocene dinosaurs
Non-avian dinosaur remains are occasionally found above the Cretaceous-Paleogene boundary. In 2001, paleontologists Zielinski and Budahn reported the discovery of a single hadrosaur leg-bone fossil in the San Juan Basin, New Mexico, and described it as evidence of Paleocene Dinosaurs. The formation in which the bone was discovered has been dated to the early Paleocene epoch, approximately 64.5 million years ago. If the bone was not re-deposited into that stratum by weathering action, it would provide evidence that some dinosaur populations may have survived at least a half million years into the Cenozoic Era. Other evidence includes the finding of dinosaur remains in the Hell Creek Formation up to 1.3 meters (51 in) above (40000 years later than) the Cretaceous-Paleogene boundary. Similar reports have come from other parts of the world, including China. Many scientists, however, dismissed the supposed Paleocene dinosaurs as re-worked, that is, washed out of their original locations and then re-buried in much later sediments. However, direct dating of the bones themselves has supported the later date, with U-Pb dating methods resulting in a precise age of 64.8 ± 0.9 million years ago. If correct, the presence of a handful of dinosaurs in the early Paleocene would not change the underlying facts of the extinction.
Any climate change causing pan-global mass extinction of Dinosaurs along with a few other animal groups namely, Ammonites, Mesosaurs, Plesiosaurs and a few Mammalian groups over a period of one million years should have, rationally speaking, resulted in near extinction of the entire flora and fauna on earth. But to the contrary there is evidence that birds survived extinction event. Flowering plants (Angiosperms) made their early appearance during this period.
There are known other mass extinction events affecting other groups of organisms, for example planktonic forms Globigerinidae suffered mass extinction at the end of Eocene only to reappear later (Cifelli 1969: Radiation of Cenozoic foraminifera, System. Zool., 18, 154 – 168).
Similarly Lazarus taxons are well known which suffered extinction at some point in time only to reappear later. One such taxon is Coelocanthus fish which reappeared in 1938 after extinction for nearly 65 million years (Wikipedia: search Lazarus taxons).
From the above account, it is self-evident that no theory explaining mass extinction of Dinosaurs due to climate change of any kind can ever be consistent with known facts.
Therefore, only two possibilities remain, either Dinosaurs suffered pan-global mass extinction as biologically timed out group of organisms or they evolved into some other group of organisms with which no ancestor – descendent relationship can be established, presently. Regarding the former possibility, Gryphaea mollusks are known to have evolved to their extinction.
The later possibility can’t be dismissed outrightly because saltatory evolution is known to occur. This has led to Punctuated Equilibrium Hypothesis of Eldredge and Gould ( Eldredge N. and Gould S.J. 1972, ‘Punctuated Equilibrium an Alternative to Phyletic Gradualism’, in Schopf T.J.M.(ed.), Models in Paleobiology, Freeman, Cooper, San Francisco).
Darwin in 1859 in his book Origin of Species by Means of Natural selection page 298 observed:-
That the periods during which species have been undergoing modification though very long as measured by years, have probably been short in comparison with the periods during which these species remained without undergoing any change
Summing up, pan-global mass extinction of Dinosaurs could not have been due to climatic change. It was essentially not the question of struggle for survival and survival of the fittest or imperfect forms struggling to perfect themselves. Therefore neither Darwinism nor Lamarckism can explain Dinosaur extinction. There are only two possibilities. Dinosaurs either evolved to other phyletic lines or organisms, with which no ancestor – descendent relationship can be presently demonstrated or Dinosaurs evolved to their extinction, alternative speaking were biologically timed out. What really happened is a matter of further investigations.