Scientists have recently announced the discovery of a small tooth in the Corral Bluffs, in the Denver basin, Colorado that shows one of the group of early mammals from which primates later emerged probably evolved in North America. For Creationists keen to find a reason to dismiss science and the evidence it keeps revealing showing creationism is nothing but an evidence free superstition, this is eerily reminiscent of what they regard as the 'Nebraska Man' hoax.
The supposed hoax was nothing of the sort and was, in reality a creationists lie intended to mislead people, perpetrated by two evangelical Christian con-men, Hank Hanegraff and Grant Jeffrey, who falsely proclaimed it to have been a failed attempt to trick people into believing in evolution - a trick that still has some success on creationists, notorious as they are for failing to fact-check their claims.
Creationists like to pretend that palaeontology is little more than a catalogue of embarrassing mistakes and hoaxes. In reality, of course, the history of palaeontology shows the opposite: new discoveries steadily refine and improve our understanding of life’s history, filling gaps in the fossil record and clarifying evolutionary relationships. A recent discovery reported in a press release by Taylor & Francis and described in a peer-reviewed paper in the Journal of Vertebrate Paleontology is a good example of this process at work.
The discovery concerns a few minuscule fossil teeth belonging to Purgatorius, a tiny, shrew-sized mammal that lived about 65.9 million years ago, shortly after the asteroid impact that wiped out the non-avian dinosaurs. Purgatorius is widely regarded as one of the earliest known relatives of the primate lineage—the group that eventually gave rise to monkeys, apes and humans. Fossils of this animal were previously known mainly from Montana and parts of western Canada, but the new finds from the Denver Basin in Colorado extend its known range several hundred miles further south.
According to the researchers, this discovery helps fill an awkward gap in the early fossil record of primate relatives. Slightly younger species appear in the southwestern United States about two million years later, leaving palaeontologists wondering why earlier forms seemed confined to the north. The Colorado fossils suggest that these early primate relatives probably spread southwards fairly rapidly after the mass extinction that ended the Cretaceous Period, diversifying as forests recovered in the aftermath of the impact.
However, before creationists begin sharpening their pencils in preparation for another round of “Nebraska Man” rhetoric, it is important to understand what this discovery does—and does not—show. The paper is not claiming that primates themselves evolved in North America, nor that this tiny mammal was a direct ancestor of humans. Purgatorius is better described as a stem relative of primates—an early member of the broader evolutionary group from which primates eventually emerged. In other words, it sits near the base of the evolutionary tree leading to primates, not within the modern primate group itself.
What the discovery really demonstrates is something far more typical of evolutionary biology: as new fossils are found, the geographical distribution and timing of early evolutionary lineages become clearer. In this case, a few teeth barely larger than grains of rice are helping palaeontologists reconstruct how the earliest primate relatives spread across ancient North America in the chaotic ecological world that followed the extinction of the dinosaurs.
Purgatorius — One of the Earliest Relatives of the Primate Lineage.The tiny mammal Purgatorius is widely regarded as one of the earliest known members of the evolutionary group that eventually gave rise to primates. It lived about 66–63 million years ago, immediately after the asteroid impact that ended the Cretaceous Period and wiped out the non-avian dinosaurs.
A Mammal the Size of a Shrew.
Purgatorius was extremely small—probably weighing 20–30 grams, roughly the size of a modern shrew or mouse. Fossils are mostly limited to isolated teeth and fragments of jawbone, which is typical for animals of this size because their delicate skeletons rarely fossilise well.
Despite their tiny size, these teeth contain a wealth of evolutionary information. Their shape suggests that Purgatorius was likely an omnivore, feeding on insects, fruit, and seeds. The teeth also show features associated with early primate relatives, particularly adaptations for a generalised diet and climbing lifestyle.
Living in the Forest Canopy
Evidence from limb bones discovered in earlier studies suggests that Purgatorius was probably arboreal, spending much of its time in trees. The hands and feet appear suited for grasping branches, an ability that later became a defining feature of primates.
This tree-dwelling lifestyle may have been important in the early evolution of primates. Forest canopies provided new ecological opportunities after the extinction of the dinosaurs, allowing small mammals to diversify into niches that had previously been dominated by reptiles and birds.
A “Stem” Relative of Primates
Although Purgatorius is closely related to primates, it is not itself a true primate. Instead, it belongs to a group of early mammals often called plesiadapiforms, which represent stem primates—species near the base of the evolutionary branch leading to modern primates.
True primates (known as euprimates) appear later in the fossil record, around 55 million years ago during the early Eocene, when forms such as Teilhardina and Notharctus appear in Asia, Europe, and North America.
Why Purgatorius Matters
Even though it was tiny and left only fragmentary fossils, Purgatorius is crucial for understanding primate evolution because it helps bridge the gap between:
- generalized early placental mammals after the dinosaur extinction
- the later emergence of recognisable primates
Each new fossil discovery helps palaeontologists refine the picture of how the primate lineage began to diversify in the forests of the early Paleocene world.
Miniscule fossil discovery reveals fresh clues into the evolution of the earliest-known relative of all primates
Purgatorius had previously only been found in the upper regions of North America, this discovery, 500 miles south, suggests they diversified soon after the mass extinction at the end of the Cretaceous
New, miniscule fossils of the earliest-known relative of all primates, including humans, Purgatorius, have been unearthed in a more southern region of North America than ever before – and the breakthrough is providing paleontologists fresh clues about evolution.
Purgatorius upper molar from Corral Bluffs Denver Basin CO.
The origin and early biogeographic history of primates is a fascinating, albeit controversial topic. The oldest archaic primate, Purgatorius, is a small, shrew-sized mammal that first appears in North America immediately after the extinction of the dinosaurs around 65.9 million years ago.
While fossil bearing rock of the right age exists throughout North America, to-date this mammal had previously only been found in present day Montana and southwestern Canada.
The next set of archaic primates include a diversity of relatives in southwestern USA, but these date to some two million years later – which has left somewhat of a puzzle… until now.
As findings, published today in the peer-reviewed Journal of Vertebrate Paleontology, report the southernmost discovery of Purgatorius fossils ever unearthed – uncovered in Colorado’s Denver Basin, at the Corral Bluffs study area.
The discovery helps fill the gap in understanding the geography and evolution of our earliest primate relatives. The presence of these fossils in Colorado suggests that archaic primates originated in the north and then spread southward, diversifying soon after the mass extinction at the end of the Cretaceous Period.
Ankle bones of Purgatorius exhibit features that indicate it lived in trees, so we initially thought its absence south of Montana could be related to the sweeping devastation of forests from the asteroid impact 66 million years ago. However, our paleobotanical colleagues suggested the recovery of plants in North America was fast leading us to believe that Purgatorius should also be in more southern regions and perhaps we simply hadn’t looked hard enough.
Associate Professor Dr. Stephen G. B. Chester, co-author
Brooklyn College and The Graduate Center
City University of New York (CUNY)
New York, USA.
To enable this deeper dive, Dr. Chester and colleagues from DMNS, deployed a careful, but extensive screen-washing technique. It was used, thanks, in part, to the support of a nearly $3 million collaborative grant from the National Science Foundation, which has funded a wider project – led by Dr Tyler Lyson at DMNS – to understand how life on Earth recovered following the mass extinction, best known for the demise of the dinosaurs.
The extensive screen-washing of sediments and picking was carried out by students and volunteers. It resulted in countless fossils of fish, crocodilians, turtles, and… eventually, a few tiny Purgatorius teeth that would fit on the tip of a baby’s finger.
What is particularly “exciting” about these teeth, explains Dr. Jordan Crowell, a postdoctoral fellow at the DMNS who also played a key role in the study, is that they could in fact belong to an earlier species of Purgatorius.
The specimens have a unique combination of features compared to known species of Purgatorius, but we are awaiting the recovery of additional material to assess whether these fossils represent a new species.
Dr. Jordan W. Crowel, co-author.
Department of Earth Sciences
Denver Museum of Nature & Science
Denver, Colorado, U.S.A.
These tiny teeth also demonstrate that the previously presumed absence of early primate relatives in more southern states of the Western Interior of North America was at least partly due to a sampling bias. Paleontologists have been finding fossils from this region and time interval using traditional surface collecting techniques for nearly 150 years, which mostly results in the collection of large fossils that are apparent to the naked eye.
Thanks to our long-term partnership with the City of Colorado Springs who own the land where the fossils were collected, as well as countless hours of work by our volunteers and interns picking through the dirt for the precious vertebrate fossils, we are building some incredible datasets that provide insights on how life including our earliest primitive primate ancestors, rebounded after the single worst day for life on Earth.
Dr Tyler R. Lyson, co-author
Department of Earth Sciences
Denver Museum of Nature & Science
Denver, Colorado, U.S.A.
The paper also includes co-author Dr. David Krause, Senior Curator of Vertebrate Paleontology at the DMNS.Our results demonstrate that small fossils can easily be missed. With more intensive searching, especially using screen-washing techniques, we will undoubtedly discover many more important specimens.
Associate Professor Dr. Stephen G. B. Chester.
Publication:
And so, once again, the fossil record continues to fill in the details of life’s long history, piece by tiny piece. In this case, the discovery of a few teeth scarcely larger than grains of rice helps clarify how the earliest relatives of primates spread through the forests that were recovering after the extinction of the dinosaurs. Far from undermining evolutionary theory, discoveries like this strengthen it by adding further detail to an already well-supported picture of gradual diversification following one of the greatest ecological upheavals in Earth’s history.
Predictably, however, those committed to defending Biblical literalism may attempt to misrepresent this research as another example of scientists supposedly “inventing” human ancestors, in the same way that creationist propaganda still recycles the long-debunked story of “Nebraska Man”. But the comparison is as misleading as it is tired. The Nebraska Man episode was a brief early-20th-century misinterpretation that was quickly corrected by scientists themselves, long before it was seized upon by a couple of unscrupulous evangelical Christian frauds and deliberately misrepresent as an 'evolutionist' hoax. It is actually a good example of the self-correcting nature of science, not a failure of it. By contrast, Purgatorius is known from multiple fossil sites and fits neatly into a broader and well-supported evolutionary framework describing the rise of primate relatives after the end-Cretaceous mass extinction.
What this discovery actually illustrates is how science works: hypotheses are refined as new evidence is uncovered, and the evolutionary story becomes clearer with every new fossil. The earliest primates did not suddenly appear fully formed, nor did they descend from a mythical single pair of specially created ancestors. Instead, like every other group of organisms, they emerged gradually from earlier lineages of small mammals that survived the extinction of the dinosaurs and exploited the ecological opportunities that followed.
For anyone willing to look at the evidence rather than cling to dogma, the message from fossils like Purgatorius is unmistakable. Life on Earth has a deep and complex history stretching back hundreds of millions of years—far longer than any literal reading of ancient mythology allows—and each new discovery brings us a little closer to understanding how our own distant lineage began.
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