O

There were reports, written at the turn of the 20th century, of |

iguanodonts from Europe (primarily France and Romania) in s rocks of very latest Cretaceous age. From the analysis above, these would not have been expected to have survived into Late Cretaceous times because everywhere else the pattern was one of hadrosaurs replacing iguanodonts. In the early 1990s, the best-preserved material came from Transylvania, a region of Romania. However, the phylogenetic analysis prompted expeditions to reinvestigate these discoveries. Fresh study proved that this dinosaur was not a close relative of Iguanodon, but represented an unusually long-lasting (relict) member of a more primitive group of ornithopods. An entirely new name was created for this dinosaur: Zalmoxes. So, one of the outcomes of the preliminary analysis was a great deal of new information about an old, but apparently not so well understood, dinosaur.

A report published in the 1950s suggested that a very Iguanodon-like dinosaur lived in Mongolia in Early Cretaceous times. This tantalizing report also needed to be investigated further to check whether its anomalous geographic range - in Asia in Early Cretaceous times - was real or, as in the Romanian example, another case of mistaken identity. The material, though fragmentary, was stored in the Russian Palaeontological Museum in Moscow, and had to be re-examined. What emerged was again not as expected. This time the earlier reports proved correct, the genus Iguanodon itself seemed to be present in Mongolia in Early Cretaceous times, and the pieces recovered were indistinguishable from the very well known European Iguanodon.

This second discovery did not fit at all comfortably with the evolutionary and geographic hypothesis that had been created in the 1984 analysis. Indeed, in more recent years a suite of very

M interesting Iguanodon-like ornithopods have emerged in Asia, ii as well as North America, in what can best be described as 8

£ 'middle' Cretaceous times. Much of this very recent, and steadily accumulating, evidence suggests that the original evolutionary and geographic model had a number of fundamental flaws that continued investigation and new discoveries were able to expose.

0 0

Post a comment