A Megatherium americanum skull fragment collected by Charles Darwin in 1832 has been rediscovered and its two pieces digitally reconnected in a 3D model. When Darwin found the specimen on a beach in Argentina, it was encased in rock (ie, the matrix) which made it difficult to see the details of the fossil. Darwin thought it was a Megatherium skull, but he couldn’t be certain.

He sent it to the Royal College of Surgeons (RCS) where Richard Owen, the first Director of the Natural History Museum, applied the Gordian Knot solution and sliced the specimen in two parts. In so doing he revealed a cross-section of the teeth was able to confirm that it was indeed a Megatherium skull fragment. The two pieces were eventually separated — the larger remaining in the RCS collection, the smaller winding up at Down House, Darwin’s home — but the destination of the smaller piece was poorly documented and the connection was lost.

The divided skull came back to the fore when researchers at the Natural History Museum were researching the three Megatherium specimens as part of a project with the ambitious goal of digitizing Darwin’s full collection of mammal fossils. They went way back to the journals of Darwin’s Argentina trip to identify the three specimens, but the the divided one didn’t match his description because of Owen’s cut. Records explained that it was a cross-section but not where the smaller piece was. They could find no records referring to it past 1845.

Having searched the Museum’s huge collection of fossil mammals for the missing fragment, and that of the RCS to no avail, curator of fossil mammals Pip Brewer and palaeobiologist Adrian Lister extended their search to Down House, the home of Charles Darwin, where they were miraculously able to locate the remaining fragment of Darwin’s Megatherium specimen. […]

On September 4 2018, both parts of the specimen were brought to the Museum where 3D specialist Kate Burton scanned both fragments using a 3D surface scanner. This scan is the first time that these fragments of the same Megatherium skull have been united in over 150 years. By scanning both fragments of the specimen, the Museum is able to make these vitally important specimens accessible to all, from scientists and educational groups to artists and enthusiasts across the globe, inspiring the next generation of natural world ambassadors.

The new scans were released on November 24th to celebrate the 159th anniversary of the publication of On the Origin of Species. Here is the Megatherium, both parts viewable together and apart so you can view the teeth in cross-section.

Oh and they have an aurochs skull! I do love an aurochs skull. They have three specimens, actually, all of them digitized. None of them were collected by Darwin, but this one, which was found near Atholl in Perthshire, Scotland, was documented by Richard Owen in 1846.