Fossils reveal how tusks first evolved and why they are unique to mammals

Warthogs, hippopotamuses, Arctic-dwelling walruses and hyraxes all have tusks More at https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=303916&WT.mc_id=USNSF_1 This is a Research News item.
Source: NSF Discoveries - Category: Science Source Type: research
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