Actinidia oregonensis facts for kids

Actinidia oregonensis was an extinct species of flowering plants. It belonged to the same family as the kiwifruit we eat today, called Actinidiaceae. Scientists only know about this plant from fossil seeds found in Oregon, USA. These fossils are from the Eocene epoch, which was about 45 to 43 million years ago.

Discovering an Ancient Plant

Where the Fossils Were Found

Scientists found Actinidia oregonensis fossils in a special place in Oregon. This area is part of the John Day Fossil Beds National Monument. The specific spot is called the Clarno nut beds. It is about 3 kilometers (2 miles) east of a small community named Clarno, Oregon.

These nut beds are very old, dating back to the middle Eocene epoch. Scientists used special methods like zircon fission track and argon–argon dating to figure out their age. They found the fossils are between 45 and 43 million years old.

The ground where the fossils were found is made of hardened sand, silt, and rock. It shows that the area was once a lake delta. Sometimes, there were also floods and volcanic mudflows, along with hot springs.

How Scientists Studied the Fossils

The first descriptions of Actinidia oregonensis came from special fossil seeds. These seeds are called "type specimens." One main specimen, UF 6292, is called the holotype. There are also five other "paratype" specimens.

Most of these fossils are kept at the University of Florida in Gainesville, Florida. Another paratype specimen is at the National Museum of Natural History in Washington, D.C.. These fossils were part of a huge collection of about 20,000 specimens. Many people, including high school students, helped collect them between 1942 and 1989.

Paleobotanist Steven R. Manchester from the University of Florida studied these Actinidia oregonensis fossils. He wrote the first official description of the species in 1994. This was published in a science journal called Palaeontographica Americana. The name oregonensis was chosen because the fossils were found in Oregon. This was the first time an Actinidia species was named from North America.

What the Seeds Looked Like

The seeds of Actinidia oregonensis had a special shape. They were symmetrical on both sides, like a mirror image. They looked like a long oval with pointed ends. The seeds were between 3.2 and 4.4 millimeters long. They were also between 2.2 and 3.0 centimeters wide.

Scientists could tell these seeds belonged to the Actinidia family because of their outer shape. They also looked at the way nutrients were supplied inside the seed. The seeds were somewhat flat, like a lens, with a ridge along the middle.

The outer layer of the seed, called the seed coat, was about 1 millimeter thick. It looked similar to the seed coats of modern Actinidia plants. It had tiny, distinct cells that got smaller towards the edges. These ancient seeds were larger than the seeds of some modern kiwifruit relatives. Examples include A. arguta, A. callosa, A. chinensis, and A. strigosa. However, they were similar in size to another fossil species, A. foveolata, found in Europe.