By "Kathleen Hunt, Stephen Jay Gould, Colin Stearn and Robert Carroll" "The Graphics are out of the Mammal evolution book"
The Condylarths are considered to be ancestors to the ungulate order which includes the hoofed mammals. They are credited to be the first herbivores mammals. The reason why these mammals were the first herbivores, are because their cheek teeth had grinding surfaces, rather than pointed cusps. The rest of their features are general such as; five toed, or clawed feet, all of their teeth were present with no gaps in between, narrow small brain, they also had all of their limb bones that were unfused.
A hyracoid-like Condylarth from the early Eocene of North America Some of the different groups of Condylarths in turn have represented separate lines of development. In the development of these separate lineages it changed over a time period of a few million years. Some of the early Condylarths were evolutionary dead ends, but some did have relationships with today's animals such as: Pigs, Whales and Horses. The interesting feature that links some of the Condylarths to early whales is the shape of the skull. Among living mammals, whales are most closely related to even-toed ungulates like pigs and cows. These mammals have a taxon in common, but in time they went their own distinct directions.
A primative phenacodontid Condylarth form the mid Palaeocene of Western USA
The most common fossil mammal from the lower Eocene is a little primitive weasel-looking
Condylarth called Hyopsodus. It was previously known that many very different
species of Hyopsodus were found at different sites, with (for example) very
different tooth size. In 1976 Gingerich analyzed the tooth size of all the known
fossils of Hyopsodus that could be dated reliably and independently. Since these
Condylarths were primitively herbivores, they are thought to live in a halfway
habitat, part forest and part savanna. The Condylarths' fossils were mainly
found in North America and Europe. It's more evidence that this mammal lived
in a part forest and part savanna conditions. The six main families of a Condylarths
are: Arctocyonidae. The most primitive of all and probably including the ancestors
of all later ungulate orders. Procungulatum is the best known member of this
group from the Upper Cretaceous. Phenacodontidae. Long-limbed genera, almost
certainly including the ancestors of the perissodactyls. Hyopsodontidae. Short-limbed
animals that were possibly the ancestors of the South American ungulates. Meniscotheriidae.
Distinguished by their complex cheek teeth but not close to the ancestry of
any later ungulates. Periptychidae. Characterized by the crenulated pattern
of the molar enamel. Some reached large size, but were not close to the ancestry
of the later groups. Didolodontidae. The only South American condylarths and
probably including the immediate ancestors of most if not all ungulate orders
that evolved on that continent.Phenacolophidae. Poorly known Asian group, probably
including the ancestorsof the elephants, a related aquatic order the Desmostylia,
and possibly an extinct African group, the Embrithopoda.
Question: What feature links Condylarths to early Whales?
Answer: Their skull.
A Condylarth close to horse and the Whale ancestry form the late Palaeocene of North America
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