Leptictidium, Indohyus and Deinogalerix

Leptictidium auderiense (Tobien 1962, Lower Eocene 50-35 mya) was once considered a bipedal omnivore with small forelimbs and elongate hind legs. Once considered an enigmatic saltator (leaper), with loose ankles and a loose sacrum-ilium joint, is now considered a tenrec and thus a stem whale ancestor. Leptictidium likely swam by paddling those long hind legs coordinated with the long tail in dorsoventral undulations. It was found in lake environment sediments. Leptitictis is more primitive. Compare it to Maiacetus.

Below: Leptictidium had the pulley-like astragalus found in whale and ungulate ankles.

Indohyus major (Rao 1971, Thewissen et al. 2007; Eocene, 48 mya; 1m in length) was considered an artiodactyl, but nests in the large reptile tree with Leptictidium between tenrecs and odontocete whales. So the case for Leptictidium as a whale ancestor is strengthened with the addition of its sister Indohyus. The case for a traditional artiodactyl ancestor for whales is much diminished.

Rao AR 1971. New mammals from Murree (Kalakot Zone) of the Himalayan foot hills near Kalakot, Jammu and Kashmir state, India. Journal of the Geological Society of India. 12 (2): 124–34.

Thewissen JGM, Cooper LN, Clementz MT, Bajpai S and Tiwari BN 2007. Whales originated from aquatic artiodactyls in the Eocene epoch of India. Nature 450:1190-1195.

Tobien H 1962. Insectivoren (Mammalia) aus dem Mitteleozän (Lutetium) von Messel bei Darmstadt. Wiesbaden: Notizbl. hess. Landesamt. Bodenforsch

Villiera B, Van Den Hoek Ostendeb L, De Vosb J and Paviaa M 2013. New discoveries on the giant hedgehog Deinogalerix from the Miocene of Gargano (Apulia, Italy). Geobios. 46 (1–2): 63–75.

wiki/Leptictidium
wiki/Indohyus

Mammalia

Ornithorhynchus and kin

Marsupials - Metatheria

Eomaia and kin

Placentalia 2

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Placentalia 1

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Notharctus and kin

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