Category Archives: Animals

Bonnerichthys

In modern oceans, the very largest organisms specialize in filter feeding, or living on the very small plankton in the water. (Read more about the filter feeding niche). Up until now, it has appeared to researcher that during the Age of Dinosaurs, when the oceans were dominated by large, toothy reptiles, there were no marine animals specializing in the niche of large-bodied filter feeding, despite ample evidence that the oceans were rich in planktonic resources.

However, this niche was in fact filled during the Mesozoic as demonstrated in a recent paper in the journal Science (Friedman et al., 2010). Turns out that several species of fish did specialize in filter feeding, and they too grew quite large. Most of the specimens were already sitting in drawers in museums, having been misunderstood for many years, until Friedman and his colleagues re-evaluated them.

For example, one species has been known for over 100 years—having been named by E. D. Cope in 1873 as ‘Portheus’ gladius from a specimen collected from the Niobrara Chalk formation in western Kansas. The Niobrara Chalk was deposited during the Late Cretaceous period (see a geologic time scale). The species has a long and complex taxonomic history, mostly of interest to professionals, but it does clearly show that many scientists reviewed the fossil material and scratched their heads in wonder about this strange set of fossils.

Friedman and his colleagues have finally put the pieces together, and it fills in much about the history of life in the oceans. They have created a new genus in which to place the species, so now it is known as Bonnerichthys gladius. The genus was named for the Kansas fossil-collecting family that collected the most complete specimen found to date.

Bonnerichthys would have been about 20 to 25 feet in length with a huge, gaping mouth. You can see an artist’s reconstruction of Bonnerichthys at Oceans of Kansas. And you can listen to an interview with Matt Friedman at NPR.

This discovery opens up a whole new understanding of the paleoecology of the Mesozoic oceans, and shows that filter feeding was utilized for at least 100 million years longer as a major life strategy than previously recognized.

FRIEDMAN, M., K. SHIMADA, L. MARTIN, M. J. EVERHART, J. LISTON, A. MALTESE, AND M. TRIEBOLD. 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science, 327:990-993.

The large consume the small

It is an interesting paradox of the natural world that some of the largest species alive survive by eating some of the smallest species.

Consider the largest animal ever known to have existed. No, it is not a dinosaur, but an animal alive today, the blue whale, Balaenoptera musculus. This behemoth can grow to over 100 feet long and weigh 380,000 pounds. And yet, this animal does not eat large fish, but tiny planktonic animals, those that float in the water.

The blue whale belongs to the suborder of baleen whales, or mysticets, that all make their living by filter feeding plankton—sucking water into their mouths and trapping the small, floating plankton to swallow. The toothed whales, or odontocets, do eat larger prey.

There are several other large vertebrate groups that also specialize in eating the very small, and they too grow to very large proportions. For example, the whale shark (Rhincodon typus), the largest living fish at about 40 feet long and weighing in at 47,000 pounds. And then there is the second largest fish, the basking shark (Cetorhinus maximus), also a filter feeder. Giant rays also feed this way.

Whale shark, the world's largest living fish

Whale shark, the world's largest living fish

So clearly, you can get very big eating small things. However, there has been a bit of a mystery in the fossil record. There has been a general lack of known filter feeding animals from the fossil record during the Mesozoic, the time of dinosaurs; clearly, that was a period in Earth’s history when things could get very large. So, where were the filter feeders?

An important piece of this puzzle has just fallen into place. Just published in Science is a paper outlining new discoveries of filter feeding fishes from the Mesozoic, and it turns out that they too were large (Friedman et al., 2010).

The fossils were mostly already in the collections of museums, having been collected in both Europe and North America. However, they were not well understood until this team began to look at them in more detail, and recognized their filter feeding adaptations. The fossils reported belong to the extinct pachycormid family, and include the new genus Bonnerichthys, named for the Bonner family of Kansas.

And in keeping with a theme, the pachycormid family of fish included the largest bony fish known, Leedsichthys, reaching over 30 feet in length in the Jurassic of Europe.

Leedsichthys, the largest spcies of fossil fish

Leedsichthys, the largest spcies of fossil fish

This latest work shows that in fact there were a number of filter feeding fish through about the last 100 million years of the Mesozoic, filling this lucrative niche held in modern times by rays, sharks, and whales. Another mystery from the past is closer to being solved.

FRIEDMAN, M., K. SHIMADA, L. MARTIN, M. J. EVERHART, J. LISTON, A. MALTESE, AND M. TRIEBOLD. 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science, 327:990-993.

Many other interesting facts can be found here at Boneblogger. Look around and enjoy.

Giant Short-Faced Bear: a Northern California Original

In 1878, James D. Richardson explored Potter Creek Cave in Shasta County, California. He found the skull of a bear beneath several inches of cave dirt, and he sent the specimen to Edward D. Cope, who determined that it was the type specimen for a new species of American “cave bear” (Cope, 1879).

Arctodus

Reconstruction of the Giant Short-faced Bear, Arctodus

When a scientist studies an animal and determines that it is something new to science, they set up a name for it and designate a type specimen. The type specimen, or type, holds a special significance as the “name bearer” for the entire species, and subsequent investigations of that species make reference to the type. They are often kept in special collections within the museums that hold them, or at least given special protection over other specimens. For example, they often are not loaned out as other specimens in the museum collection might be, so there is less risk of damage. (For a description of geologic type sections, see formations).

All too often the type specimens of fossil species have been based on fragmentary material or poor descriptions, making a full understanding of the species more difficult. A famous example of this is the story of the dinosaur Apatosaurus.

Apatosaurus was named by Cope’s rival, O. C. Marsh (Marsh, 1877). Both Cope and Marsh were rushing to describe more fossil species than the other, and their famous rivalry led to shoddy work by both men on occasion. Marsh said the type specimen of Apatosaurus was a “nearly complete specimen in excellent preservation.” However, he only briefly described the vertebrae of this new animal in his haste to publish the new name.

Later, Marsh published the name Brontosaurus, with a few comments on the pelvis and vertebrae of that type (Marsh, 1879). Brontosaurus soon became widely known to the public, and to many, represented the quintessential dinosaur. However, by 1903 Elmer Riggs recognized that Apatosaurus and Brontosaurus were in fact the same species of dinosaur, and since Apatosaurus was named two years before Brontosaurus, that name had priority and was the name that should be used (Riggs, 1903). However, the old name Brontosaurus was in such popular usage that it took many decades for the public to catch on. Now, it seems that every young dinosaur buff knows of this name change and is comfortable with it.

Since the first Short-faced Bear fossil to be recognized in North America was from Northern California, the type specimen, and the name of the bear, Arctodus simus, will be forever linked to the region. This “American Cave Bear” is now known from over 100 localities from Alaska to Mexico, east coast to west (Richards et al., 1996). It was a wide-spread species of the late Pleistocene Ice Age.

What is perhaps most striking about this bear is its size. Arctodus is the largest mammalian carnivore ever discovered. It is larger than any of the modern bears, tigers, or lions by a significant degree. An estimate for the largest Arctodus found to date suggests that if the individual was “lean” it weighed from 1,300 to 1,400 pounds (Nelson and Madsen, 1983). In contrast, a male lion weighs about 450 pounds. (See How big was the GSFB?)

So this imposing carnivore of the Ice Age roamed across North America, and the North State can forever claim it as its own. A full skeletal mount of this beast can be seen in the new Gateway Science Museum at Chico State.

COPE, E. D. 1879. The cave bear of California. American Naturalist, 13:791.

MARSH, O. C. 1877. Notice of new dinosaurian reptiles from the Jurassic Formation. American Journal of Science, 14:514-516.

MARSH, O. C. 1879. Notice of new Jurassic reptiles. American Journal of Science, 18:501-505.

NELSON, M. E., AND J. H. MADSEN, JR. 1983. A giant short-faced bear (Arctodus simus) from the Pleistocene of northern Utah. Transactions of the Kansas Academy of Science, 86(1):1-9.

RICHARDS, R. L., C. S. CHURCHER, AND W. D. TURNBULL. 1996. Distribution and size variation in North American short-faced bears, Arctodus simus, p. 191-246. In K. M. Stewart and K. L. Seymour (eds.), Palaeoecology and Palaeoenvironments of Late Cenozoic Mammals: Tributes to the Career of C.S. Churcher. University of Toronto Press, Toronto.

RIGGS, E. S. 1903. Structure and relationships of opisthocoelian dinosaurs. Part
1: Apatosaurus Marsh. Field Columbian Museum, Geological Series, 2:165-196.

Related Posts:
How big was the GSFB?
Denning behavior
GSFB reexamined

New species are still being uncovered at the Gray Fossil Site

Dr. Steven Wallace holds the beaver tooth recently discovered at the Gray fossil site. (Brian Bishop / Johnson City Press)

The Gray Fossil Site near Johnson City, Tennessee is full of surprises. The site dates to the late Miocene in age, and preserves a diverse fauna of critters. It is highly unusual to have deposits of this age preserved in the Appalachian region as most of the sediments have been stripped away from the underlying crystalline bedrock. But in this unusual setting, sediments that filled a sinkhole were preserved, along with a lot of evidence of past life from the region.

Researchers have not yet “scratched the surface” of the deposit despite several years of excavation. Core samples indicate that the deposit covers several acres and is over 100 feet thick (Wallace et al., 2002). Many species have been identified from the site including: fish; alligator; snakes; turtles; amphibians; a proboscidean; the world’s largest single collection of tapirs; rhinos; a short-faced bear; ground sloth; a saber-toothed cat; and a red panda.

They have recently added beaver to the list.

Steven Wallace and his team have identified the specimen as Dipoides, a member of an extinct line of beavers which includes the giant beaver Castoroides. Dipoides has a stratigraphic range extending from the Hemphillian to the late Blancan (Kurten and Anderson, 1980), or approximately 9 million to 3 million years ago (Prothero, 1998).

Today, you can visit a large interpretive center at the site, and watch summer excavations. It is expected that an annex will be started soon to provide even more space for visitor activities. Check it out on line at www.grayfossilmuseum.com, and watch for continued news coming from Johnson City, Tennessee in paleontology.

References:

KURTEN, B., AND E. ANDERSON. 1980. Pleistocene Mammals of North America. Columbia University Press, New York, 443 p.

PROTHERO, D. R. 1998. The chronological, climatic, and paleogeographic background to North American mammalian evolution, p. 9-36. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary Mammals of North America. Cambridge University Press, New York.

WALLACE, S. C., J. NAVE, AND K. BURDICK. 2002. Preliminary report on the recently discovered Gray Fossil Site (Miocene), Washington Co., Tennessee: with comments on observed paleopathologies and the advantages of a large sample. Journal of Vertebrate Paleontology, 22(Supplement to Number 3):117A.