Apatosaurus different dinosaur individuals. Among the many notable differences are the widerand presumably strongerneck of "Apatosaurus" species compared to "B.excelsus". Other species previously assigned to "Apatosaurus", such as "Elosaurus parvus" and "Eobrontosaurus yahnahpin" were also reclassified as "Brontosaurus". Some features proposed to separate "Brontosaurus" from "Apatosaurus" include: posterior dorsal vertebrae with the centrum longer than wide; the scapula rear to the acromial edge and the distal blade being excavated; the acromial edge of the distal scapular blade bearing a rounded expansion; and the ratio of the proximodistal length to transverse breadth of the astragalus 0.55 or greater. Sauropod expert Michael Daniel
Dinosaur egg and a system of classification based on the structure of eggshell was developed in China before gradually diffusing into the West. Dinosaur eggshell can be studied in thin section and viewed under a microscope. The interior of a dinosaur egg can be studied using CAT scans or by gradually dissolving away the shell with acid. Sometimes the egg preserves the remains of the developing embryo inside. The oldest known dinosaur eggs and embryos are from "Massospondylus", which lived during the Early Jurassic, about 190 million years ago. In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern