September 23: edit
- 1832 - During the second voyage of the HMS Beagle, Charles Darwin collected fossils in the Punta Alta, Argentina area, including the skull of a large rhinoceros-like mammal.
- 1953 - Kenneth Garrett was born in Columbia, Missouri, USA.
- 1972 - Norman Arthur Wakefield died as a result of a fall from a tree while trimming its branches at his home in Sherbrooke, Victoria, Australia at age 53.
- 1989 - Edna P. Plumstead died in Johannesburg, South Africa.
- 2014 - Washington Luiz Silva Vieira and others performed a statistical analysis of titanosaur biodiversity and co-occurrence in South America during the Late Cretaceous, finding that the coexistence of titanosaurs at various times and places in Late Cretaceous South America were essentially random rather than driven by ecological factors like niche partitioning.