The cladogram represented by the large reptile tree (LRT) shows that at more than one time within the clade Mammalia, sharp, clawed unguals became broad, often hoofed, unguals. And then several times broad unguals once again became sharp claws. Here’s the pattern:
Small basal mammals all had sharp claws. So did basal monotremes, marsupials and placentals.
Ernanodon, among the marsupials, had broad, round unguals
Toxodon, among the marsupials, had short, anteriorly concave unguals, perhaps supporting hoofs.
Basal placentals, including Carnivora and Glires, had sharp claws. Primates, like Proconsul,developed fingertip pads surrounding their unguals with only the keratinous nails exposed.
Alcidedorbignya, among pantodont placentals (basal herbivores), had proto–hoofs (tips nearly as wide as bases). In the same clade, so did Pantolambda.
Bayrlambda, among basal xenarthrans, had short unguals, barely longer than wide.
Paramylodon, a ground sloth, had long sharp claws, but Glyptodon, a sister had truncated unguals, more like hoofs.
Bradypus, a tree sloth, had long, curved, sharp claws. So did Orycteropus, Dasypus and kin.
Titanoides, a basal phenacodont had sharp claws.
Phenacodus, another basal phenacodont, had round hoof-like unguals. Many subsequent large mammalian herbivores had similar hoof-like unguals, except…
Mysticete whales, like Balaenoptera, had long sharp unguals hidden within their flippers.