At the time, Turner was on the search for features related to ancient cyanobacteria. In the study, author Elizabeth Turner, a sedimentary geologist at the Laurentian University, Sudbury, Canada, described finding rocks from the said area a few decades ago. This dilemma would find itself in the middle of recent scientific discussions once again right in the middle of 2021: a couple of rocks found in the Northwest Territories of Canada, discovered back in the 1990s but only recently reexamined, might just contain the oldest evidence yet of animal life, according to recent findings in a study submitted to the journal Nature. Such is the nature of science and research-to seek and find, then doubt if you do.

Other times, scientists do find fossils in rocks relatively close to the dates determined by MCD, yet other scientists scrutinize whether or not the “fossils” in question were really fossils at all. This, then, leads to two possibilities: either the age determined by MCD is wrong or the dates from MCD were actually roughly correct, but fossilization of the animal in question would be a rare occurrence due to their invertebrate nature. Oftentimes, looking for rocks dated to an age range estimated by MCD yields empty rocks with no fossils to speak of. This, then, presents a dilemma: it’s one thing to determine when a kind of animal first appeared using MCD finding the evidence for these animals in rocks of the same age as that determined by MCD, however, are an entirely different matter. MCD involves examining the rate of change of an animal’s DNA and/or proteins due to mutations alongside comparisons of a target’s DNA with those of other modern organisms doing so gives a relative estimate of when the animal first appeared. (Bones wouldn’t appear in the fossil record until much later for a similar reason, ancient cartilaginous fish, like ancient sharks, are only identifiable from their fossilized teeth-the parts of their body most resistant to the geological stresses induced by fossilization.) Yet, somehow, there are fossil impressions of ancient invertebrates, like jellyfish, that posses no “hard” body parts to speak of these instances, however, are very rare occurrences, and require very specific conditions that these animals must be in at the time of their deaths before fossilization can occur-and even then, the best that we can get as fossils are impressions of their body parts locked in place in sedimentary rock (or entire bodies, if we get extremely lucky).įor this reason, scientists often have to resort to other techniques like molecular clock dating ( MCD) to determine when these kinds of animals first appeared on Earth.

Admittedly, it is a challenge: being invertebrates with no shells or exoskeletons, these simple animals don’t possess any “hard” body parts like bones that can easily be left behind after their deaths to fossilize over eons of time. Thought to be the first animals to ever branch off the family tree hundreds of millions of years ago, their traces are among the first features in old rock paleontologists look for when finding the oldest evidence of life on Earth. These simple animals appear almost amorphous in shape, have no discernable internal organs, and seemingly lack the basic body symmetries most other animals in the family tree exhibit. It’s been long presumed by many scientists the world over that modern-day sponges-the humble and porous sea creatures made famous by a certain geometric cartoon character that lives inside a undersea pineapple-belong to the oldest lineage of animals.

Oldest animal age