According to Wikipedia
Artiocetus (Gingerich et al. 2001; meaning essentially = artiodactyl + whale) was the first fossil to show that early whales possessed artiodactyl-like ankles (Fig. 1). The sizes, shapes and configurations are indeed similar. And this was a valid conclusion, but it was based on taxon exclusion. Other taxa have such ankles.
Figure 1. A selection of two whale ankles and one artiodactyl (Antilocapra, the pronghorn antelope). Such comparisons are the basis for aligning whales with artiodactyls, but tenrecs were not considered.
Contra the artiodactyl hypothesis
the large reptile tree nests the basal whale, Maiacetus, with a clade of small and large, extinct and extant tenrecs like Hemicentetes, Andrewsarchus and Leptictidium.
So, to shed light on this disparity
here are two whale feet and ankles alongside the foot and ankle of Hemicentetes (Fig. 2), the tenrec without a tail (some other tenrecs have long tails (Figs. 5, 6), but extant examples don’t have online skeletons).
Figure 2. The evolution of the tenrec (Hemicentetes) pes, through the land whale Rhodhocetus and Basilosaurus. Rhodocetus loses pedal digit 1. Basilosaurus loses pedal digit 2. Note the lack of sharp claws and the lack of artiodactyl hooves in all taxa. Note the plantigrade pes here, not the digitigrade pes of artiodactylus. Note the reduction of distal tarsals (cuneiforms) down to dt3 (lateral cuneiform) in all taxa.
To the credit of the tenrec-whale clade:
Figure 3. A basal artiodactyl, Ancodus, pes. As in Rhodhocetus pedal digit 1 is absent and the distal tarsals are reduced to one. This led to the artiodactyl hypothesis, and that is a great first guess! But it is not supported by the LRT.
To the credit of the artiodactyl-whale clade hypothesis:
Figure 4. Maiacetus is a basal whale with legs and it is also a giant tenrec. Compare Leptictidium (Figs. 5, 6).
Artiodactyls came to the mind of Gingerich first
because artiodactyls had similar ankles to his land whale discoveries and were of similar size. Few workers both to study tenrecs — but tenrecs should have been included as they have similar pedes and taxon exclusion often arises with enigma taxa, as whales were.
Figure 5. Elements of Leptictidium from Storch and Lister 1985. Note the long calcaneal heel here.
Figure 6. Leptictidium – Often considered a kangaroo like hopper (saltator), the loose sacral connection and phylogenetic bracketing suggest this was a dorsoventral undulatory swimmer instead.
Figure 7. Science magazine cover for Gingerich et al. 2001. Artist: John Klausmeyer. The hands and feet are far from being ungulate hooves, but close to tenrec paws.
Gingerich PD, Haq M, Zalmout I, Khan I and Malkani M 2001. Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan”. Science. 293 (5538): 2239–42.