Horselike Fossil From 48 Million Years Ago Preserved While Pregnant

A forty eight-million-yr-old horselike fossil discovered close to Frankfurt. Credit Franzen et al./Senckenberg Analysis Institute

A forty eight-million-yr-old horselike fossil pulled from the rich Messel Pit site close to Frankfurt is yielding insights into the evolution of mammalian reproductive systems. A fetal specimen described in  brand new research is the earliest and finest-preserved mammalian fetus so far.

“The query was, is it possible that the placenta was preserved?” asked Jens Lorenz Franzen, a retired paleontologist affiliated with the Senckenberg Museum in Frankfurt and one of the research authors.

In looking at the fossilized soft tissue, he and his colleagues found a preserved placenta, uterus and one broad uterine ligament — proof, Dr. Franzen stated, that the ancient mare had a reproductive system similar to that of a modern horse.

This implies a sophisticated reproductive system was already present in mammals at the time of Messel, he stated.

The bones of the fetus are additionally intact apart from the cranium, which is crushed.

The findings appear within the journal PLOS One.

The fetus was first discovered in a fossilized mare found in 2000 by Dr. Franzen and his colleagues. They studied the bones and anatomy of the fetus using scanning digital microscopy and high-resolution micro-X-ray.

The researchers consider that because the fetus is very developed, the mare could have died shortly earlier than she would have given birth.

The Eocene freshwater lake of Messel developed inside a volcanic crater and, because of the eruption, there could have been excessive levels carbon dioxide present, Dr. Franzen mentioned. The mare was in an area with an excessive amount of carbon dioxide and too little oxygen, Dr. Franzen stated.

“Possibly she came to the lakeshore to drink, lost consciousness, fell into the water and floated to the place where she was found,” he mentioned.

Supply: Horselike Fossil From 48 Million Years Ago Preserved While Pregnant