- Prosynthetoceras (23–16.9 Ma): A small deer-like animal that lived in North America and Asia. It was about the size of a modern muntjac and had antlers with three tines.
- Synthetoceras (16.9–5 Ma): A larger deer than Prosynthetoceras that also lived in North America and Asia. It had antlers with four tines.
- **Euprox* (16.9-5 Ma): A deer that lived in North America and Asia. It was similar in size to Synthetoceras but had more complex antlers.
- Sinomegaceros (12.5–2 Ma): A large deer that lived in Asia. It was the largest deer ever, standing up to 2.4 m (7 ft 10 in) at the shoulder and weighing up to 1,500 kg (3,307 lb). Sinomegaceros had massive antlers with up to 14 tines.
These ancient deer species are thought to be the ancestors of modern moose, as well as other deer species. Over time, these species evolved to adapt to different environments and eventually gave rise to the modern moose that we know today.