Clarno Nut Beds

Forty-four million years ago, central Oregon was a hot, wet, semitropical place filled with a wide diversity of plants. More than 175 species of fruits and nuts preserved in the fossil record suggest a forest more diverse than any modern ecosystem in this part of the world. It contained plants with modern relatives such as walnuts, chestnuts, oaks, bananas, magnolias, and palms. The forest was dense and moist, receiving an annual rainfall of three meters (almost 10 feet). But this semitropical environment was home to more than just trees and plants; the forest echoed with the buzzing of insects, the calls of birds, and the footfalls of mammals.

Most of the mammalian organisms that thrived during this time period are only vaguely familiar to us now: creodonts – large meat-eaters similar to wolves or hyenas but related to neither; Hyrachyus – a distant relative of the tapir; and brontotheres – large rhino-like plant eaters. In addition to the mammals, reptiles such as crocodiles and tortoises lived alongside large catfish relatives.

 

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Mural by Larry Felder

 

Key to mural

 

Dominant fossils found in this assemblage:

1. Cercidiphyllum (tree)
2. Ensete (banana plant)
3. Sabalites (extinct fan palm)
4. Patriofelis (cat-like creodont, the size of a modern panther)
5. Macginicarpa (sycamore)
6. Orohippus (early horse)
7. Dioon (cycad)
8. Cornus (flowering dogwood)
9. Juglans (walnuts)
10. Pinus (pine tree)
11. not labeled in mural
12. Pristichampsus sp. (3 m long crocodile)
13. Ictalurus cf. (freshwater catfishes)
14. Telmatherium (1.25m brontothere)
15. Castanea (chestnut)
16. Magnolia (magnolia tree)
17. Hyrachyus (‘running rhino’)
18. Lauraceae (laurel tree)
19. Cicadidae on Vitis (cicada on grapevine)
20. Meliosma (aguacatillo)

 

Mesonychid, a meat-eating hooved mammal, was found within the Clarno unit.

Scans by Selina and rendering by MacGregor Campbell/OPB, used with permission

Flora

The Clarno Nut Beds flora is predominantly made up of angiosperms (flowering plants) like magnolias, walnuts, kiwi, bananas and others. The beds also contain gymnosperms (produces seeds without fruit) like Gingko sp., Yews, and more. The Nut Beds also preserve over 66 genera and 77 species of petrified woods, making it the most species rich fossil wood locality on Earth of any age.

Fauna

Patriofelis ferox was a creodont, an extinct group of carnivorous mammals, similar to the size of a modern panther. Patriofelis translated from Latin means “father cat,” but this refers to superficially similar anatomy, rather than a relationship to the cat family (Felidae). It first appeared in the middle Eocene some 45 million years ago. It had short legs with broad flat feet, suggesting that it may have been a poor runner, but a better swimmer and climber. Because it belongs to an extinct family of carnivorous mammal and with no modern analogs, it is difficult to determine the locomotion style (the way it walked) of Patriofelis.

Pristichampsus sp. was a crocodile that lived alongside many mammals 44 million years ago. It had heavily armored skin and long legs, suggesting it was a cursorial (adapted to running) reptile that spent most of its time hunting terrestrial mammals. Pristichampsus’ teeth were sharp and had serrated edges, characteristic of modern terrestrial crocodiles.

Orohippus major was a three-toed horse that likely had great agility and maneuverability. It was about the size of a Border Collie, diminutive by comparison with other modern horses. Orohippus had an enlarged middle toe, a defining equine trait. However, this browser would look more like a prehistoric deer because of its small size and low-crown teeth.

Hyrachyus eximius was a perissodactyl (odd-toed ungulate) mammal related to the modern tapirs and rhinoceroses. It would have looked similar to a tapir, but probably lacked the tapir’s proboscis (trunk) as there is no evidence preserved in the nasal bones which would have been retracted to support this. Hyrachyus' teeth resembled those of a rhino, suggesting its ecological role as a ground dwelling browser.

For complete lists of fossils found at the Clarno Nut Beds, e-mail us.