A 48 million-year-old fetus has been discovered in a fossil of an ancient pregnant horse-like creature near Frankfurt, Germany, according to a study published Wednesday in the U.S. journal Plos One.
The pregnant creature and its fetus were uncovered at a well-known fossil treasure trove called Messel pit in 2000.
Researchers examined the mother's remains using scanning electronic microscopy (SEM) and high-resolution micro-x-ray and found a 12.5-cm fetus.
"The fetus is the earliest and best-preserved fossil specimen of its kind," said the study led by Jens Lorenz Franzen of the Senckenberg Research Institute, in Frankfurt, Germany.
According to the study, the fetus is almost complete with almost all bones present and connected, except for the skull, which appears to have been crushed.
The well-preserved condition of the fossil allowed the researchers to conclude that the mother may have died shortly before giving birth, but the death was probably not related to birth.
The researchers also found preserved soft tissue, like the uteroplacenta and one broad uterine ligament, which may represent the earliest fossil record of the uterine system of a placental mammal.
"Evidently, the uterine system developed much earlier, at the latest during the Paleocene (66 to 56 million years ago) but more probably already during the Mesozoic (252 to 66 million years ago)," they wrote.
