[8] Fossils found from the Cerrejón Formation are the earliest record of Neotropical rainforests, with an abundance of plant macrofossils and palynomorphs.

The Cerrejón Formation also records a riverine vertebrate fauna that includes lungfish, turtles, snakes, and crocodyliforms.

Based on the size of the giant boid Titanoboa, specimens of which have been found in the Cerrejón Formation, the mean annual temperature of Paleocene equatorial South America was between 30 °C (86 °F) and 34 °C (93 °F).

[9] It is consistent with Paleocene climate models which predict greenhouse temperatures and an atmospheric pCO2 concentration of around 2,000 parts per million.

This may be an indication of the early stage of Neotropical diversification, or a delayed recovery period following the Cretaceous–Paleogene extinction event.

[2] Many plants from the Cerrejón Formation belong to families that are still common today in modern Neotropical rainforests.

[15] The presence of these types of flora in Paleocene strata shows that plants characteristic of modern Neotropical rainforests have existed for geologically long periods of time, being able to withstand climatic and geographic changes in South America.

It has been suggested that today's Neotropical rainforests are the result of environmental changes brought about by Quaternary glacial cycles (i.e. the recent ice age).

[16] However, the floral record from the Cerrejón Formation shows that the current diversity of the Amazon Rainforest can be traced back into the early Cenozoic.

One survey of plant macrofossils showed that around half of the studied specimens had been attacked by herbivorous insects.

There is no evidence of the elevated insect-feeding diversity or host-specialized feeding associations that are seen in later Neotropical forests.

[2] Remains of the giant boid Titanoboa cerrejonensis have been found from a gray claystone layer underlying Coal Seam 90 in the Cerrejón mine.

Anthracosuchus likely had massive jaw muscles allowing it to feed on large turtles, a behavior which is corroborated by predation marks found at the site.