Complex sentence: He decided to give this specimen a new name because conventions and the relatively sparse fossil record at that time meant that features then used to distinguish genera and species have now been found to be more widespread among sauropods.
Split into simpler sentences: He decided to give this specimen a new name based on the conventions of his age and the relatively sparse fossil record at that time discovered. Later it was recognised that the features he used to distinguish genera and species are in fact more widespread among sauropods.