Acer whitebirdense facts for kids

Acer whitebirdense was an extinct type of maple tree. It's known from fossil leaves and seeds (called samaras). These fossils were found in places like Idaho, Oregon, and Washington in the United States. This ancient maple belongs to a group of maples called Rubra, which still has living members today.

Discovering the Ancient Maple

Scientists found fossils of Acer whitebirdense in different parts of the United States. These places include central Idaho, northeastern Oregon, and central and eastern Washington state. The very first important fossil, called the holotype (a key example specimen), was found in White Bird, Idaho. Both leaves and seeds were discovered there.

More seeds were also found in the Latah Formation near Grand Coulee, Washington. Other finds were made in Spokane, Washington. In Oregon, scientists Wolfe and Toshimasa Tanai found leaves and seeds near Baker. They also noted seeds from the Stinking Water area.

Scientists used special dating methods in 2012. They found that the rocks where these fossils were found are about 15.6 to 14.8 million years old. This means Acer whitebirdense lived during the Middle Miocene epoch.

How it Got its Name

The leaves that are now called A. whitebirdense were first described in 1932. A scientist named Thomas Ashlee thought they were from a different plant, a Viburnum species. He named them "Viburnum" whitebirdensis.

Later, other scientists looked at the fossils from White Bird. Edward W. Berry described some leaves as A. florissanti and Platanus dissecta. He also found a seed he called A. oregonianum. In 1937, Roland W. Brown described White Bird leaves as Acer osmonti.

Some scientists, like Ralph Chaney and Daniel Axelrod, even thought some leaves might be from a Rubus (like a blackberry) plant, not a maple.

When scientists Wolfe and Tanai re-examined all the White Bird fossils, they realized something important. They concluded that all these different fossils actually belonged to just one type of maple tree. Since Ashlee's name, "Viburnum" whitebirdensis, was the oldest name given to these fossils, they moved it to the Acer group. That's how it officially became Acer whitebirdense.

Family Tree of Maples

Based on how the veins looked in the fossil seeds, Wolfe and Tanai thought A. whitebirdense might have come from an older maple. They believed it could be a descendant of A. kenaicum, a maple from the Oligocene period in Alaska.

They also thought that a later maple, A. taggarti, might have come from A. whitebirdense. This was based on how similar their leaves looked. The seed structure of A. whitebirdense is similar to a living North American maple, A. saccharinum (the silver maple). However, their leaves are different.

Scientists placed A. whitebirdense into a group called Acer section Eriocarpa. Later, this group was included in a larger section called Rubra.

What it Looked Like

Leaves

The leaves of A. whitebirdense were simple in shape. They had veins spreading out like fingers from the base, like a fan. Their overall shape was round. Each leaf had five lobes. The two upper-middle side lobes were about three-quarters as long as the main middle lobe. The two outermost side lobes were half as long as the upper-middle ones. All the lobes were somewhat round or triangular.

These leaves were quite big! They ranged from about 7 cm (2.8 inches) to an estimated 20 cm (7.9 inches) long. Their width could be anywhere from 7.0 cm (2.8 inches) to 29.0 cm (11.4 inches). Each leaf had five main veins. There were also many smaller veins that formed a network, creating irregular shapes and quadrangular (four-sided) areas.

Seeds (Samaras)

The fruits of A. whitebirdense were samaras, which are winged seeds. They had a small, hard part at the bottom, called a nutlet, and a wing extending upwards from it. The nutlet was elliptical (oval-shaped) and measured about 1.0 to 2.7 cm (0.4 to 1.1 inches) long. It had a scar where it attached to the wing, about 0.2 to 0.7 cm (0.08 to 0.28 inches) long.

Five to seven veins spread out from this attachment scar across the nutlet. They then came together slightly at the tip of the nutlet before continuing into the wing. The wings were between 1.0 and 4.0 cm (0.4 to 1.6 inches) long and had a broadly curved upper side. The nutlet was about one-third the length of the whole samara.

Scientists Wolfe and Tanai thought that because the nutlet was so close to the base of the wing, these seeds might not have spun well in the wind. This means they probably didn't float far away. Instead, they suggested that animals might have helped spread the seeds, or they simply fell straight to the ground near the parent tree.