Organic Matter: Study gives teeth to evolution theory

Evolution is a topic that tends to spark debate in the scientific community, and an Associated Press story last week added some additional fuel.

A study, published Dec.

28 in the journal Nature, suggests that specialized teeth which enabled ancient, shrew-like animals to survive and gave rise to all modern mammals evolved independently in two animal groups on different continents.

The study was headed by Zhe-Xi Luo of the Carnegie Museum of Natural History.

Three paleontologists examined fossilized teeth and bones of mammals which lived 65 million to 200 million years ago for the study.

In comparing characteristics of the teeth, they concluded that advanced molars which ensured the success of the small creatures evolved in two mammal groups on northern and southern continents.

Earlier theories held that the specialized molars, which can simultaneously shear food and crush it, evolved only in the Northern Hemisphere.

However, recent fossil finds in Madagascar and Australia offer clues suggesting a southern origin for the dual-function molars.

I enjoy watching wildlife programs on Animal Planet and the Discovery Channel.

Narrators of such programs often talk about survival strategies of different species, strategies that evolved long before man's appearance and rise to become the dominant species on Earth.

According to the study, advanced teeth of the animals equipped them with an edge by allowing them to eat a broader range of foods than more primitive creatures.

While many scientists hailed the study, some cautioned that more fossil evidence is needed to support or refute the findings.

Leonard Krishtalka, a professor of ecology an evolutionary biology at the University of Kansas, said the study's conclusion is a bold hypothesis which takes dental evidence about as far as possible.

Unless you are a paleontologist or historian this may not be of interest to you.

But as some people believe man evolved from lower forms of life in the sea, could there have been a sort of parallel evolution with humans developing teeth more suited to a life on land than creatures of the ocean?

An intriguing thought.

Luo and two colleagues examined fossils of 21 early mammals that ranged in size from shrews to small raccoons.

They agreed that a dual north-south evolution of the advanced tribosphenic teeth came about following a split of the supercontinent Pangea into northern and southern continents 160 million years ago.

A recent fossil find of a jaw fragment in Madagascar seems to challenge mammal evolution theories.

Three advanced molars discovered in the late 1990s are thought to be 167 million years old, which is 25 million years older than all previous tribosphenic fossils.

John J.

Flynn, co-discoverer of that fossil and a curator at the Field Museum of Natural History in Chicago, said the new study is "the first volley of what will be a very interesting debate" regarding mammal evolution.

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Another story on fossils made headlines last week as regards the remains of "Kennewick Man" found in 1996 in the shallows of the Columbia River in Washington state.

The U.S.

Army Corps of Engineers plowed over a burial site where a 9,300-year-old skeleton was found.

Corps spokesmen said they were trying to protect the site from looters when they covered it with 500 tons of rock and soil in 1998.

But eight scientists sued the Corps last week, saying it had violated the National Historic Preservation Act.

The scientists argue the action violates laws governing preservation of historical artifacts and has risked ruining the original burial site.

Oral arguments in the case are scheduled for June 19.

Regardless of which side wins in court, I find the action taken here troubling.

The motive of protecting a historical site from looters is good, but was plowing it over the only solution?

Is funding not available from some source to erect a chain-link fence topped with barbed wire as we have around the Mohave County Fairgrounds? What about a 24-hour security guard patrolling the site?

Let's not destroy history in the name of preserving it.

Terry Organ is the Miner's education, health and weather reporter.