embryo fossil

Embryo fossil found in South Africa is world's oldest proof that mammal ancestors laid eggs

2026-04-13 02:10:00 UTC

250-Million-Year-Old Embryonated Dicynodont Egg Found in South Africa | Sci.News

2026-04-13 02:10:00 UTC

Using high-resolution CT and synchrotron scanning, paleontologists confirmed that the fossilized specimen from the Early Triassic of the South African Karoo Basin contains an unborn dicynodont Lystrosaurus, resolving a long-standing mystery about whether early mammal ancestors laid eggs.

Proto-mammals laid eggs, paleontologists finally confirm

2026-04-13 02:10:00 UTC

Lystrosaurus fills in a major evolutionary gap.

embryo_fossil

Embryo fossils are the preserved remains of unhatched or unborn organisms. Many fossils of the 580 million year old Doushantuo Formation have been interpreted as embryos; embryos are also common throughout the Cambrian fossil record.

Taphonomic studies indicate that embryos are preserved for longest in reducing, anoxic conditions. These conditions can keep the embryos intact for long enough for bacteria to mineralise the cells and permit their preservation. However, phosphatisation was very rapid in the Doushantuo, so it is possible that faster preservation allowed embryos in different regimes to be preserved.