We rely on smell more than most people may realize. Across mammals, scent guides feeding, warns of danger, and shapes social behavior. A new international study shows that this vital sense leaves a lasting mark in bone, allowing scientists to estimate how well even extinct mammals could smell. The research was led by Dr. Quentin Martinez and Dr. Eli Amson at the State Museum of Natural History Stuttgart. Their team combined brain anatomy with genetic data to reveal a clear link between skull shape and olfactory ability…….Continue reading….
By: Joshua Shavit
Source: The Brighter Side of News
.
Critics:
Like living elephants, mammoths typically had large body sizes. The largest known species like Mammuthus meridionalis and Mammuthus trogontherii (the steppe mammoth) were considerably larger than modern elephants, with mature adult males having an average height of approximately 3.8–4.2 m (12 ft 6 in – 13 ft 9 in) at the shoulder and weights of 9.6–12.7 tonnes (21,000–28,000 lb), while exceptionally large males may have reached 4.5 m (14 ft 9 in) at the shoulder and 14.3 tonnes (32,000 lb) in weight.
However, woolly mammoths were considerably smaller, only about as large as modern African bush elephants with males around 2.80–3.15 m (9 ft 2 in – 10 ft 4 in) high at the shoulder, and 4.5–6 tonnes (9,900–13,200 lb) in weight on average, with the largest recorded individuals being around 3.5 m (11 ft 6 in) tall and 8.2 tonnes (18,000 lb) in weight.
The insular dwarf mammoth species were considerably smaller, with the smallest species M. creticus estimated to have a shoulder height of only around one metre (three feet) and a weight of about 180 kilograms (400 lb), making it one of the smallest elephantids known. The number of lamellae (ridge-like structures) on the molars, particularly on the third molars, substantially increased over the course of mammoth evolution.
The earliest Eurasian species M. rumanus have around 8–10 lamellae on the third molars, while Late Pleistocene woolly mammoths have 20–28 lamellae on the third molars. These changes also corresponded with reduced enamel thickness and increasing tooth height (hypsodonty). These changes are thought to be adaptations to increasing abrasion resulting from the shift in the diet of mammoths from a browsing based diet in M. rumanus, towards a grazing diet in later species.
Following the end of the Last Glacial Maximum, the range of the woolly mammoth began to contract, disappearing from most of Europe by 14,000 years ago. By the Younger Dryas (around 12,900-11,700 years Before Present), woolly mammoths were confined to the northernmost regions of Siberia. This contraction is suggested to have been caused by the warming induced expansion of unfavourable wet tundra and forest environments at the expense of the preferred dry open mammoth steppe, with the possible additional pressure of human hunting.
The last woolly mammoths in mainland Siberia became extinct around 10,000 years ago, during the early Holocene. The final extinction of mainland woolly mammoths may have been driven by human hunting. Relict populations survived on Saint Paul island in the Bering Strait until around 5,600 years ago, with their extinction likely due to the degradation of freshwater sources, and on Wrangel Island off the coast of Northeast Siberia until around 4,000 years ago.
The last reliable dates of the Columbian mammoth date to around 12,500 years ago. Columbian mammoths became extinct as part of the end-Pleistocene extinction event where most large mammals across the Americas became extinct approximately simultaneously at the end of the Late Pleistocene. Hunting of Columbian mammoths by Paleoindians may have been a contributory factor in their extinction.
The timing of the extinction of the dwarf Sardinian mammoth Mammuthus lamarmorai is difficult to constrain precisely, though the youngest specimen likely dates to sometime around 57–29,000 years ago. The youngest records of the pygmy mammoth (Mammuthus exillis) date to around 13,000 years ago, coinciding with the reducing of the area of the Californian Channel Islands as a result of rising sea level, the earliest known humans in the Channel Islands, and climatic change resulting in the decline of the previously dominant conifer forest ecosystems and expansion of scrub and grassland.
Leave a Reply