Thomas Henry Huxley ("Darwin's bulldog"), who was a comparative anatomist, made a study of it nearly 150 years ago. He compared the first fossil bird, "Archaeopteryx", with "Compsognathus". These two fossils were found in the same rocks: Solnhofen limestone in Bavaria, Germany. The strata come from the end of the Jurassic, about 144 million years ago. Huxley showed that the two were almost identical, except for the front limbs and feathers of "Archaeopteryx". He showed the basic affinity of birds and reptiles, which he united them under the title of "Sauropsida". Huxley concluded that birds evolved from small carnivorous dinosaurs.