May 25, 2021 | Jerry Bergman

Mammals Were Never Primitive

Careful Evaluation Again Reveals “Primitive” Life is Not Very Primitive
A New Study to Support Evolution Gives Evidence Against Evolution


by Jerry Bergman, PhD


A major prediction of evolution is that life that lived long ago is far less advanced than life living today. It is a logical conclusion of the belief that life evolved from the simple to the complex. The title of a book on the evolution of the brain declared, “From the Sea Sponge to CRISPR: How Our Brain Evolved.” As the book asserted, according to evolution everything living likewise evolved along the path humans took – from a simple sponge to every kind of complex creature.

I have often noticed a trend. Careful research on “primitive” mammals often finds they are more advanced than previously assumed by evolutionists. A “primitive” mammal, by evolutionary definition, would be clearly a mammal, but a less-advanced mammal than modern mammals. Consequently, evolutionists would expect primitive mammals to have traits which give evidence that they evolved from their less-advanced evolutionary precursors.

This pattern (i.e., finding that ancient animals that were assumed to have primitive traits were in-fact not-so-primitive) was repeated in a recent article in Science Daily about ankle and foot bones of a putative prehistoric mammal.[1] The article concludes:

Analysis of bones that form part of the ankle and the heel of the foot reveal that mammals during … the Paleocene Period — were less primitive than previously thought…. Their findings show that Paleocene mammals had stockier, more muscular builds than those from the Cretaceous or present day. The animals’ joints were also very mobile, supported by ligaments and tendons — rather than bony features as in some living mammals… Many species’ ankles and feet closely resembled those of ground-dwelling and burrowing mammals that exist today, indicating that these lifestyles were key to surviving and thriving.”[2]

By carefully evaluating more data, the researchers found that the previous belief was wrong:

Our results show that the prevailing archaic typecast of Paleocene mammals is a misconception. Instead, Paleocene mammals are characterized by robust limb proportions compared to extant mammals.[3]

Figure 1. Phenacodus, an example of a ‘Paleocene’ mammal.
Drawn by Heinrich Harder (1858-1935). From Wikimedia Commons. Note: colorations and soft parts are not preserved in the fossils, and skeletons are not always complete.

The website Select Science repeats the pattern: “Analysis of bones that form part of the ankle and the heel of the foot reveal that mammals during this time – the Paleocene Period – were less primitive than previously thought.”[4]

Another report came to the same conclusion, writing that a detailed analysis of ankle and heel bones revealed that these mammals which were living during the “Paleocene Period were less primitive than previously thought.[5]

Dr Sarah Shelley, of the University of Edinburgh School of GeoSciences, who led the study about early mammals, observed how evolutionists once believed the Paleocene mammals were historically

often seen as ‘archaic’ and unspecialized precursors to living mammal groups. What we found was this incredible diversity — they’re adapting and evolving their robustly built bodies in ways that are different to living mammals. Our results show one of the many ways mammals were able to adapt and thrive following the catastrophic devastation of the end-Cretaceous extinction.[6]

Figure 2. Hyracodontidae. Another example of a ‘Paleocene’ mammal.
Drawn by Heinrich Harder (1858-1935). From Wikimedia Commons. Public Domain.

Although admitting that “Little is known about the paleobiology of the mammals that diversified immediately after the extinction during the Paleocene,” Dr Shelley opined that mammals living at this time were “perceived [by evolutionists] as ‘archaic’ precursors to extant orders.”[7]

Furthermore, mammals today employ an “array of locomotor behaviors, from cursoriality in ungulates and branch-swinging in primates, to deep-diving in cetaceans and powered flight in bats.” Consequently, their locomotion tells us a great deal about them. Also revealing about the write-up is the acknowledgement that much about the alleged early evolution of mammals eludes Darwin disciples. Shelley admits that

relatively little is known about the ecomorphological diversity and paleobiology of the mammals that thrived after the [K-Pg] extinction …. The nature of mammal diversification following the K-Pg extinction is contentious. Most extant placental mammal orders cannot be traced back in the fossil record to the interval immediately following the extinction. … [their] fossil record, whose relationships to extant groups are poorly resolved and whose paleobiology is difficult to study because most species are poorly represented, often solely by teeth, and lack any obvious extant analogues. [8]

The Shelley study referenced here appears to be based on a large amount of fossil evidence, specifically

a dataset comprising 29 tarsal measurements: 17 astragalar and 12 calcaneal. Tarsals allow for accurate locomotor inferences and are commonly preserved as fossils, allowing for the incorporation of a broad sample of Paleocene taxa that better encapsulate a range of morphological diversity. Tarsal measurements were [also] taken for 85 extant therian mammals representing 20 orders.[9]

Figure 3. Mesohippus. Yet another example of a ‘Paleocene’ mammal.
Note how all of the examples drawn look very much like a modern horse.
Drawn by Heinrich Harder (1858-1935). From Wikimedia Commons.

Therian mammals taxonomically belong to a subclass of mammals that includes the eutherians of which the placental mammals are a part, and the metatherians which includes the marsupials. Furthermore, Shelley et al. observed:

The Paleocene mammal fauna is often perceived from two philosophical standpoints. On the one hand, it is the product of classic adaptive radiation marked by the proliferation of eutherian mammals more ‘advanced’ than their Cretaceous antecedents. On the other hand, many Paleocene mammals have been regarded as ‘primitive’ and ‘archaic’ forms compared with their extant relations, a view especially prominent in the historical literature. Seldom are Paleocene mammal fauna considered on their own objective merit.[10]

The ‘Evolution’ of the Theria

Much debate exists about the evolutionary origin of the theria.[11] One of the earliest known therian mammal fossils is Darwin-dated back to the Late Jurassic. Molecular data suggests that therians may have originated even earlier, during the supposed Early Jurassic. As explained by one of the most detailed reviews of therian origins:

The timing of the origin of Mammalia is poorly constrained. This is largely due to the incomplete and scarce nature of mammalian fossils from the Jurassic and Early Cretaceous and to disagreements regarding the relationships among basal mammals. There is current debate about whether mammals originated in the Late Triassic, but are poorly sampled in the fossil record at this time, or much later during the Middle Jurassic, when a diversity of unequivocal mammals first appear in the fossil record. Resolving this debate in part hinges on resolving the phylogenetic positions of enigmatic Triassic–Jurassic mammaliaforms.[12]

Figure 4. Tingamarra, an extinct placental mammal which looks very much like a dog with a mouse head. Its fossil remains are known from Australian ‘Pleistocene’ deposits. From Wikimedia Commons.

One theory is that therians evolved from the Boreosphenida, early mammals that originated in the Northern Hemisphere and had tribosphenic molars, which allows shearing and grinding in a single stroke.[13] This theory is murky. One authority wrote about Boreosphenida that it was part of  families that appeared in the Late Triassic, “Haramiyidae and Theroteinidae, [which] could be the oldest known mammals, but are also problematic. Both have been suggested to have possible affinities with multi-tuberculates because of dental resemblance.”[14]


Many conclusions of evolution are based less on data than evolutionary suppositions. When large data sets are evaluated, the conclusions tend not to support the evolutionary view, but instead the creation interpretation. Evolutionists see the world through their Darwinian glasses until more objective data forces them to look at the world for what it really is. The Shelley study is one of many examples. The entire issue of the evolution of mammals is also very problematic; but that is a topic for another paper.


[1] University of Edinburgh, Ankle and foot bone evolution gave prehistoric mammals a leg up, Science Daily, 13 May 2021.

[2] University of Edinburgh, 2021.

[3] Shelley, Sarah, Stephen L. Brusatte, and Thomas E. Williamson, Quantitative assessment of tarsal morphology illuminates locomotor behavior in Paleocene mammals following the end-Cretaceous mass extinction. Proceedings of the Royal Society B: Biological Sciences 288(1950): DOI: 10.1098/rspb.2021.0393, 12 May 2021.

[4] Li, Diane, Industry News: Ankle and foot bone evolution gave prehistoric mammals a leg up, Select Science, 13 May 2021.

[5] Varshney, Shweta, Ankle and foot evolution gave mammals a leg up, Samachar Central, 13 May 2021.

[6] University of Edinburgh, 2021.

[7] Shelley, et al., 2021

[8] Shelley, et al., 2021.

[9] Shelley, et al., 2021.

[10]  Shelley, et al., 2021. Emphasis added.

[11] Kielan-Jaworowska, Z., Evolution of the therian mammals in the Late Cretaceous of Asia. Part VII. Synopsis, Palaeontologia Polonica 46:173-183, 1984.

[12] Williamson, Thomas E.,  Stephen L. Brusatte, and  Gregory P. Wilson,

The origin and early evolution of metatherian mammals: the Cretaceous record. Zookeys 465:1–76.

doi: 10.3897/zookeys.465.8178, 17 December 2014.

[13] Davis, Brian, Evolution of the tribosphenic molar pattern in early mammals, with comments on the “Dual-Origin” Hypothesis, Journal of Mammalian Evolution 18, 227,, 28 July 2011.

[14] Anonymous, Boreosphenida, Fossil Hunters, 21 December 2020.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

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