A small and interesting plant-eating reptile called Lystrosaurus is in the news recently because it was found to have laid eggs (as reptiles do). So what’s interesting about that? Well, conventional scientists claim Lystrosaurus is a 250-million-year-old mammal ancestor called a synapsid.¹ They see this discovery as an exciting evolutionary development in the process of reptiles evolving into mammals. But a closer examination shows this discovery is actually unremarkable. Not only is it not a transitioning mammal ancestor, but Lystrosaurus also doesn’t make sense in the evolutionary timeline.

Thanks to advanced synchrotron X-ray and X-ray microcomputed tomography (CT) scanning, the scientists found an embryo within a partially preserved shell of a Lystrosaurus egg that had been found in South Africa. They stated this demonstrates “oviparity [egg-laying] for the first time in early synapsids [supposedly mammal-like reptiles].”¹ Thus, evolutionists are excited about Lystrosaurus and the implication that this “mammal ancestor” laid eggs: “This extraordinary fossil represents the first-ever egg discovered from a mammal ancestor, finally answering a long-standing question: Did the ancestors of mammals lay eggs? The answer is yes.”²

But the early synapsids, like Lystrosaurus, are acknowledged to be reptiles and “the majority . . . do not show a unidirectional progression toward the mammalian condition.”³ So, Lystrosaurus was not an evolutionary ancestor of mammals because synapsids aren’t mammal-transitioning reptiles. It laid eggs simply because it was a reptile.

The evidence actually confirms Lystrosaurus was a reptile. In fact, the evolutionists in the PlosOne article stated, “the lower jaw symphysis remains unfused—a developmental trait found only in pre-hatching embryos of modern birds and turtles.”¹ In other words, it’s a developmental trait not found in mammals. Additionally, vertebrate paleontologist Michael Benton does not refer to Lystrosaurus as a mammal but instead calls it an anomodont and dicynodont—both of which are nonmammalian.⁴

Besides being a true reptile, this creature does not fit into the conventional timeline because of one oft-overlooked component: mummification. Like soft tissue, mummification is no friend to the millions of years evolution requires.⁵ Mummified carcasses are organic (carbon-based) and can therefore be only thousands, not millions, of years old at the most. So the claim that the South African Lystrosaurus was a 250-million-year-old mummified fossil can’t be right.

To conclude, the reptile Lystrosaurus was an egg-layer as God created it in the beginning, not a distant evolutionary ancestor of mammals we have today. Furthermore, the mummification of this animal points to a youthful age. It could never have been preserved without a rapid and deep burial by the Flood about 4,500 years ago.

References

1. Benoit, J., V. Fernandez, and J. Botha. 2026. The First Non-Mammalian Synapsid Embryo from the Triassic of South Africa. PLOS ONE. 21 (4).
2. Wits University. Mammal Ancestors Laid Eggs—and This 250-Million-Year-Old Fossil Proves It. Phys.org. Posted on phys.org April 9, 2026.
3. Woodmorappe, J. 2001. Mammal-Like Reptiles: Major Trait Reversals and Discontinuities. Journal of Creation. 15 (1): 44–52.
4. Benton, M. J. 2024. Vertebrate Paleontology, 5th ed. Hoboken, NJ: John Wiley & Sons, Inc, 199, 201.
5. Thomas, B. Published Reports of Original Soft Tissue Fossils. Institute for Creation Research. Posted on ICR.org September 17, 2018.

* Dr. Sherwin is a science news writer at the Institute for Creation Research. He earned an M.A. in invertebrate zoology from the University of Northern Colorado and received an honorary doctorate of science from Pensacola Christian College.