Much of the second day was taken up with excavating a large skull which Darwin found embedded in soft rock, and seemed to him to be allied to the rhinoceros. On 8 October, he returned to the site and found a jawbone and tooth which he was able to identify using Bory de Saint-Vincent's "Dictionnaire classique". He wrote home describing this and the large skull as "Megatherium" fossils, or perhaps "Megalonyx", and excitedly noted that the only specimens in Europe were locked away in the King's collection at Madrid. In the same layer he found a large surface of polygonal plates of bony armour. His immediate thought was that they came from an enormous armadillo like the small creatures common in the area. However, from Cuvier's misleading description of the Madrid specimen and a recent newspaper report about a fossil found by Woodbine Parish, Darwin thought that the bony armour identified the fossil as "Megatherium".   </ref> With FitzRoy, Darwin went about across the bay to Monte Hermoso on 19 October and found numerous fossils of smaller rodents in contrast to the huge Edentatal mammals of Punta Alta. In November at Buenos Aires, he "purchased fragments of some enormous bones" which he "was assured belonged to the former giants!!", and subsequently took any chance to get fossils "by gold or galloping".