As one gets closer to the base of major radiations = clades
taxa begin to look more and more alike because they become more and more closely related.
Here are four basal placental skulls,
Notharctus, Anagale, Tupaia and Ptilocercus (Fig 1) that were at the genesis of Primates (including bats), Odontoceti (including tenrecs and moles) and Glires (including multituberculates) respectively.
Figure 1. Three closely related taxa, each one at the base of its own clade within Placentalia: Notharctus, Anagale Tupaia and Ptilocercus.
There was a time on this planet
when these four were among the only placentals running around. Then, as the Jurassic dragged on, each one gave rise to its own long list of progeny. They all saw plenty of dinosaurs, usually sleeping, as these four arboreal taxa clambered around after dark.
References
Blainville HMD 1838. Recherches sur l’anciennete des Mammiferes insectivores a la
surface de la terre; précéddées de l’histoirc de la science a ce sujet, des principes de leur classification et de leur distribution géographique actuelle. Comptes Rendus Hebdomadaires de Séances de I’Académie des Sciences, 6:738–744.
Le Gros-Clark WE 1926. On the Anatomy of the Pen-tailed Tree-Shrew (Ptilocercus lowii.) Proceedings of the Zoological Society of London 96: 1179-1309.
DOI – 10.1111/j.1096-3642.1926.tb02241.x
Gregory WK 1920. On the structure and relations of Notharctus, an American Eocene primate. Memoirs of the American Museum of Natural History, new series 3(2):49-243.
Leidy J 1870. Descriptions of Palaeosyops paludosus, Microsus cupidatus and Notharctus tenebrosus. Proceedings of the Academy of Natural Sciences, Philadelphia 22:111-114
Raffles TS 1821. Descriptive Catalogue of a Zoological Collection made on account of the Honourable East India Company, in the Island of Sumatra and its Vicinity, under the Direction of Sir Thomas Stamford Raffles, Lieutenant-Governor of Fort Marlborough; with additional Notices illustrative of the Natural History of those Countries. The Transactions of the Linnean Society of London (Linnean Society of London) XIII: 239–340.
Simpson GG 1931. A new insectivore from the Oligocene, Ulan Gochu horizon, of Mongolia. American Museum Novitates 505:1-22.
The Pterosaur Heresies 