A Guide to the Dinosaurs of Colorado

Dinosaur Extinction
Other Theories

While this possibility cannot be easily refuted, it seems unlikely, given the nature of the lava flows that make up the Traps. These flows were caused when the Indian subcontinent passed over the Chagos Archipelago plume as India drifted north to collide with Asia. (For a more complete discussion of Plate Tectonics and the action of plumes, see "The ABC's of Plate Tectonics" on my personal Website. --dlb)

The Deccan Traps were produced over a span of some 500,000 years by basaltic fissure flows, very similar to the eruptions that regularly occur in Iceland. Basalt has little trapped gas in it, and tends to erupt non-explosively, rather flowing smoothly, and sometimes nearly continuously, much like the current round of eruptions in Kilauea, Hawaii. Where plumes lie under continents, they do tend to produce occasional, but very infrequent, explosive events, leading to the formation of a caldera, which eventually fills in with fissure flow basalt. Yellowstone National Park lies in just such a caldera, and sometime in the next few thousand or tens of thousands of years, Yellowstone will be covered over by fissure flow basalts. The basalts of the Snake River Valley mark the location of past calderas, now obliterated by fissure flow lavas. In fact, the Snake River Basalts and the Yellowstone Park are a currently active example of exactly the process which formed the Deccan Traps. This process is really quite common in the geological history of the Earth, and only coincidently seems to be associated with a mass extinction. Certainly we are not suffering, nor have suffered in the recent past, from an ecological collapse caused by the Snake River Basalts or the Yellowstone Caldera.

Aside from the fact that no such planet has been discovered, and the fact that a 26 million year orbit that is eccentric enough to pass through the Oort cloud would carry the body far enough from the Sun to be itself perturbed by the gravitational attraction of other nearby stars, the Raup and Sepkoski data itself has some statistical problems. One problem is that while the data fits rather closely for the last three mass extinctions (K/T at 65 million years ago (Mya), the Late Eocene at 38 Mya, and the mid-Miocene at 12 Mya), as well as an event they report at the end of the Cenomanian Age (early Late Cretaceous) at 91 Mya, the 'fit' becomes more and more problematical the farther back it goes. Also, they only look at data for the last 250 million years, which barely includes the end-Permian extinction. The Late Ordovician event, the second most severe extinction known, and the fourth worst event, the Frasnian/Famennian extinction, lie nowhere near a 26 million year periodicity, at 448 and 367 Mya, respectively.

Another problem with the Raup and Sepkoski data is that they counted all the families and genera that vanished from the fossil record within a geological 'age', and plot them all as having become extinct at the end of that age. (A geological Age is a subdivision of an Epoch (e.g. Eocene, Miocene), which in turn is a subdivision of a Period (e.g. Cretaceous, Jurassic).) Therefore, what is really being reported is a periodicity in the dates assigned to the boundaries between geological ages. Now, there has been developed and generally agreed upon a standard definition of the geological ages, epochs, and periods, and reasonably accurate boundary dates assigned to each. The average interval assigned to the ages of the Mesozoic era is between 6 and 7 million years. The Raup and Sepkoski data therefore suggest that every fourth age had, on average, a statistically higher number of families and genera become extinct. (There are exceptions even in their own data.)

The assignment of geological ages is an international standard, but paleontologists working in a particular region still prefer to assign names to time intervals based on their own local conditions. The boundaries given for these local intervals is generally based on the presence or absence of diagnostic 'marker' fossils. These boundaries only rarely coincide with the boundaries of standardized geological ages, yet are based on the local extinction of one or more fossil lineages in that region. If these fossils are not also known from other regions, their disappearance counts as an extinction, even though it is only local in scope. The fact that these local systems do not widely coincide with standard ages suggests that not all extinctions coincide globally, and the basic assumption that all extinctions within a geological age occurred simultaneously at the end of that age becomes highly suspect. (The phenomenon has already been discussed that some mass extinctions appear to have been quite protracted, often spanning several million years.)

The "Death Star" theory also shares the other flaws already discussed for the giant meteor impact theory: the absence of an iridium spike, or any other evidence of an extraterrestrial impact, for any mass extinction except the K/T; the apparent gradual die-off of species before the putative impact; and the dramatic and persistent change in climate that appears to have accompanied several of the extinction events.

It is true that temperatures appear to have been universally warmer during the Age of Dinosaurs, so perhaps it was the Sun exiting from a dust cloud, resulting in global cooling, that caused the K/T extinction. It would have had to be an awfully big dust cloud, however, as the Jurassic and the Cretaceous, nearly 150 million years, both appear to have been warm.

Robert Bakker may be the most outspoken, and perhaps the most colorful, paleontologist alive today, but apparently he was unfamiliar with the theory of Plate Tectonics. (Henry Osborn most certainly was not aware of it; Plate Tectonics wasn't formally described until 1961.) At the end of the Cretaceous, Europe and North America were closer to the equator than they are today, and much closer to each other; the Atlantic Ocean had only recently begun to open. At lower latitude, the Pacific Ocean is much wider, the Atlantic at the time was much narrower, and the Bering Peninsula just wasn't long enough to have reached across (see Note 7).

The notion that large animals can cross land bridges, but smaller animals cannot is also absurd; smaller animals simply take longer. Opossums and armadillos, scarcely holders of land speed records, migrated across the Panama land bridge from South America. Nor is the idea that marine organisms died out because of the drying up of shallow inland seas reasonable. Sea levels today are no higher than they were at the K/T boundary, and there are still abundant enough shallow sea environments to support a rich variety of organisms. Also, epidemic diseases may wipe out large segments of a population, but rarely if ever has disease caused the complete extinction of a species, let alone an entire lineage of dozens of genera.

Again, the disease 'theory' fails to explain any of the environmental changes that occurred at the K/T boundary, such as changes in climate. Nor does it offer an explanation of why sea levels dropped in the first place.

Could new species of mammals have evolved at the end of the Cretaceous Period that were even more efficient egg stealers than their predecessors? Quite possibly.

Could mammals have eaten ALL the dinosaur eggs (or at least enough of them to cause dinosaurs to become extinct)? No way!

Could early mammals have caused all of the mass extinction that occurred at the K/T boundary? Don't be absurd.

First of all, mammals, or at least their immediate ancestors, the synapsids, sometimes called "mammal-like reptiles," considerably predated the dinosaurs. Dinosaurs competed with, and evolved along side of, mammals or near-mammals for all of their 150+ million years of existence. It is difficult to imagine that dinosaurs would have survived for so long if they couldn't defend their nests from predators. Dinosaur nests have been found in numerous locations, and in at least one case (Maiasaura in Montana), evidence was found suggesting parental care and feeding of the hatchlings.

Secondly, dinosaurs, at least in the case cited above, appear to have nested in large rookeries, with many nests together, each separated by about one adult dinosaur-length. This undoubtedly made predation more difficult, as a predator would have to run the gamut of many dinosaur feet to get to any but the outermost nests.

The notion of mammals causing the extinction of dinosaurs is mammalian chauvinism, by members of one mammalian species (mankind) who want to think that their ancestors somehow triumphed over the "terrible lizards" after all. This position is difficult to defend when dinosaurs were so successful in their competition with mammals for the entire time that dinosaurs lived. (It could also be pointed out that this theory fails all the criteria for a successful mass extinction theory, by not even addressing the marine species that disappeared at the K/T boundary, or any other mass extinction event.)

Concluding Article:
The Author's Own Theory