Courtesy Natural History Museum London, copyright holder not found
The exclusivity of the Two Medicine Formation's Einiosaurus finds is fairly amazing in itself. Additionally, the fact that the animals are almost always found in large groups is quite amazing as well. The fact that herds lived and died together is quite interesting and the evidence of herds that lived and died together in Einiosaurus is much more clearly evident than in say Triceratops, who are almost exclusively found as single animals (though fossil trackways thought to be from Triceratops hint toward herding behaviors). Einiosaurus, as a herding animal, makes sense in depictions as a family unit like this illustration here. As we all know, in a herd it makes sense to keep the children nearby, and so depictions with young and adult Einiosaurus together are somewhat common. Notice the difference in the juvenile and adult skull, these are supported by fossil evidence. The body of Einiosaurus is very typical of ceratopsians in almost all regards save the forward curving of the horn which certainly served some defensive and, most likely, courtship role in the life of Einiosaurs, especially given that we have not discerned a difference (to my knowledge) between male and female Einiosaurs as yet.
The skeletons of Einiosaurus are, as stated above, not sexually dimorphic as far as I have seen; anyone that knows better is certainly encouraged to share! The evidence for juveniles, however, is a little more obvious from some of the fragments, at least, that have been discovered in massed fossil deposits and allows us to at least make an educated guess concerning what is missing. Thus representations, skeletally rather than in illustrations, are also able to be made as reconstructions. The posing of skeletons in museum displays always makes them that much more believable and as unbelievable as Einiosaurus is to begin with with that forward curving horn, the ability to be posed with a baby makes it much more realistic and entertaining. These skeletons represent juvenile and subadult Einiosaurus of a family. The subadult in this image is called Xenia and is one of the most complete Einiosaurus skeletons ever found, and therefore not a conjecture on the makeup of the subadult skeleton or skull and the juvenile is called Ben and is made of a complete skull and a good portion of the post cranial skeleton; these two specimens are very important for studying how the animal changed as it grew from infancy to adulthood.