The Pull of the Recent (POR) describes a phenomenon in which a combination of factors causes palaeontologists to overestimate diversity towards the present day.
[5] However, further exploration of the data, for bivalves at least, showed that this was mostly the result of errors and unresolved taxonomies and that when these were corrected, the effect of the POR dwindled to 9%, and then to 5% when more recently discovered taxa were added.
Researchers counted the proportion of extant elasmobranchs that have a fossil record, but also have a gap in the last 5 million years in the Pliocene and Pleistocene.
[7] The fossil record of terrestrial vertebrates which include amphibians, reptiles, mammals, and birds, is not significantly effected by the Pull of the Recent (POR).
[2] A comprehensive study showed that the expansion of tetrapod biodiversity in the past 120 million years is a real biological pattern.