Anatomy of a perinatal woolly mammoth (Mammuthus primigenius) from Niederweningen (Late Pleistocene), Switzerland

Here we report on the anatomical re-investigation of a Late Pleistocene (Middle Würmian Interstadial, MIS 3, ca. 40–50 ka BP) perinatal woolly mammoth excavated in 1890-91 from Niederweningen, Switzerland, the first perinatal mammoth ever scientifically studied. In order to narrow down its age at death we compare perinatal woolly mammoths and African elephants in terms of their (i) ontogenetic allometry, especially in woolly mammoths from Russia, (ii) bone microstructure, (iii) tooth eruption sequences, and (iv) the timing of cranial suture closure. A distinct layer of postnatal bone deposition in the tibial midshaft and maxilla identified using micro-CT scanning, in particular, provides strong evidence of a post-natal ontogeny despite the lack of obvious wear in the dentition, suggesting an age of no more than a few months. Odontochronologically, the individual probably belongs to Jachmann’s (1988) Dental Stage 1 (3 months - 2 years), and tiny pits in the enamel/dentin tips of lamellar edges are analogous to those seen in juvenile M. primigenius from Russia (“Lyuba”), and are variously hypothesized to be caused by initial wear, spalling, dissolution pitting, incomplete mineralization, or eruption through the gums. Additionally, we describe anisomelia of uncertain aetiology, resulting in the stunting right fore-leg, perhaps contributing to the cause of its death. Finally, we discuss the significance to ecology and extinction of an altricial life-history strategy and the relatively rapid post-natal growth evidenced in woolly mammoths, a taxon with an exceptionally long gestation period.