德国发现一具4800万年历史的马形胎儿化石

A 48 million year-old horse-like equoid fetus ¹ has been discovered at the Messel pit near Frankfurt, Germany according to a study published October 7, 2015 in the open-access journal PLOS ONE by Jens Lorenz Franzen from Senckenberg Research Institute Frankfurt, Germany, and Naturhistorisches Museum Basel, Switzerland, and colleagues. The authors of this study completed their investigation ² of the fetus from a 48 million year-old horse-like equoid uncovered near Frankfurt, Germany in 2000. They evaluated the bones and anatomy ³ and used scanning electronic microscopy (SEM) and high-resolution micro-x-ray to describe the ~12.5 cm fetus. The fetus appears to be well-preserved, with almost all bones present and connected, except for the skull ⁴, which appears to have been crushed. The well-preserved condition of the fossil allowed the researchers to reconstruct the original appearance and position of the fetus. They estimate that the mare ⁶ may have died shortly before birth, but don't believe the death was related to birth. , ,The authors 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. Applying SEM, the authors discovered a bacterial ⁷ lawn replacing the soft tissues, as is common with other specimens ⁸ found in that area. The observable details correspond largely with living mares, which lead the authors to posit ⁵ that the reproductive system was already highly developed during the Paleocene, and possibly even earlier.