Digging Sideways For Science

Recently we received the question on our blog, “How far down do you have to dig to get to the Cretaceous-Tertiary boundary?” A similar question that I get in anthropology and paleontology is “How far down do you dig to find a T. rex…..or a Dimetrodon….or an Australopithecus?”

We usually don’t dig down. We dig SIDEWAYS!

Fossils are not that common. You could rent a back-hoe and dig at random in North Texas for a month and not find anything. You need to find those few, special layers that have bones or shells.

So….the best way is to use Nature’s Bulldozer.

Here’s how it works. Nature cuts into rock layers using rivers and streams. River banks and the sides of arroyos show us cross-sections of the rock. We use these natural cuts to search for the layers rich in fossils.

Edaphosaurus pogonias

My HMNS crew has walked, hunched over, for days at a time, scrutinizing the banks of gullies in North Texas, without seeing a thing worth digging. But we must have patience. In the Permian Red Beds, for instance, we do find new sites on average every two days. Last month, we found four spots that had bones of the fin-back Edaphosaurus, one of the earliest plant-eaters that ever evolved.

We didn’t dig those four spots because the bones were few and fragmentary.

But we found a fifth spot in the bank of a gully that had a whole vertebral column of the fin-back Dimetrodon, the top predator of the time. Here we dug in, sideways, and recovered a large part of the skeleton, including hips and shoulder.

To get the Cretaceous-Tertiary transition fossils, we go to Raton, New Mexico. Here steep river banks expose the sediments from 65 million years ago, when the dinosaurs went extinct. We can dig in sideways and excavate thin zones of black clay that preserve pollen and spores from the plants that lived just before and just after the great dino extinction.

To find fossil hominids in Africa, first we’d search aerial photos, looking for cuts made by rivers and streams into sediments laid down about 2 million years ago.

Think “Sideways.”

If All the Dinos Died on One Terrible Weekend – Where are All the Bodies?

asteroid
Creative Commons License photo credit: goldenrectangle

According to the Impact Theory, a rock from space smashed into the earth, threw up a huge dust cloud, chilled the atmosphere and sent down acid rain.  All the dinosaurs died immediately all over the globe or in a week or so.

So….where are the bodies of the victims?

Probability of Becoming a Fossil: 0%     or    100%

0%
If you die on a high plateau or a grassy meadow or on the average forest floor, far from the influence of river floods, your bones will get chewed, cracked, smashed and digested by scavengers. The remnants will get dried up and will flake away to nothing under the sun. Or, if the ground is wet, worms and grubs and fungi will destroy your osseous remnants.

That happens to most dead bodies, most spots, most of the time. Or…

100%
What if you’re lucky enough to die in a depositional basin, where yearly floods bring in layers of sand, silt and mud, and where lake bottoms accumulate blankets of sediment all the time. A place where huge sand bars develop in streams and rivers….

….then the possibility that some of your bones will get buried and fossilized rises to close to 100%.

Dino Extinction Supposedly Hit While Montana Was Getting Sediment
At the time of the Great Dino Die-Off, no sediment was being laid down in most places in the world. But in Montana’s Cretaceous coal fields, there were many swampy lakes and sluggish rivers, locales where mud and sand was being carried in. This depositional activity seems to have continued right through the end of the Cretaceous and beginning of the next Period, the Tertiary (“Age of Mammals”).

In fact, field geologists have a hard time telling where the Cretaceous mud ends and rhe Tertiary mud begins.

20090222_9115
Creative Commons License photo credit: etee

If the Impact Theory is right, millions of Triceratops carcasses littered the landscape. Tens of millions of duck-bill dino bones also covered the ground. And….there were no big scavengers to crack the bones. The average dino body would last far longer than usual. Some of the impact victims should have had a high probability of being buried in the mud at the Impact Layer, the sand and silt and mud deposited right after the rock from the sky struck.

Total number of dino bones found right at the Impact Layer – 00.00.

That’s  one reason why I am an Impact Skeptic. You have to do some special pleading to explain the lack of dino bones at the impact layer. You could argue that soil acid dissolved the bones. Or that for a hundred years there was no new mud, no new sand, no new silt.

Could be.

Still, I like to begin with a geological peshat (first impression): When I scan the actual facts on the ground, there is no evidence whatever of a sudden massive death of dinosaurian multitudes at the Impact Layer.

I dinosauri a Cremona
Creative Commons License photo credit: Simone Ramella

Evidence for a Long, Slow Disaster
There are clues that indicate the dino ecosystem was deteriorating long before the impact. The diversity among big, multi-ton dinos went way down about 5 to 10 million years before the end. In the Latest Cretaceous (Lancian Age) in most places in Montana, there are only two common big dinos – either Triceratops or the duckbill Edmontosaurus. It was a dino-monoculture.  At 76 million years ago diversity was much higher.

Serial Killer in Deep Time
The biggest reason I’m a skeptic is the victim profile. When the dinos finally went extinct, salamanders, frogs, pond turtles, river gators all survived and thrived. So did most small terrestrial species. That pattern holds for six other mass extinctions – beginning at 285 million ears ago, long before the first dino. And the pattern is obvious in the last extinction at the end of the Ice Age, 11,000 years ago.

Impact Theory Fails to Predict the Correct Victim Profile
Sudden chill and acid rain will wipe out salamander-oids and frog-oids and turtle-oids. And hit big, active animals far less severely.

The wrong animals died.

Read about my dinosaur extinction theory in an early blog post.