Hopson focused his research
on the origin of mammals. His work indicated that mammals descended from a single lineage of mammal-like reptiles. His work on tooth replacement in mammal-like reptiles was one of the first to show that growth patterns and dental anatomy can be used to study these extinct species.
On the side
Hopson served as the expert editor for my book, “From the Beginning, the Story of Human Evolution” (Peters 1991). Shortly thereafter, in the late 80s Dr. Hopson was kind enough to host my field trip to Chicago. He showed me the collections there and at the Field Museum. Dr. Hopson also provided reams of photocopies of his work on synapsids. Much of that went into the book, which remains largely accurate today. You can read the book online in PDF form here.
about Jim Hopson and his contributions to vert paleo here.
A note about the Liaoning bird embryo from a few days ago…
Dr. Zhou was kind enough to send a high resolution image of the specimen and I have updated the imagery and conclusions posted here on the Liaoning bird embryo. In short, the embryo now nests with the holotype (London specimen) of Archaeopteryx, which nested and still nests as a basal enantiornithine bird. Happily, this analysis confirms both the original identification of the embryo as an enantiornithine, AND a close relationship to Archaeopteryx.
High resolution will get you there,
but low resolution can still get you close…