Typical search radius?

[zoocosmolina]

Not exactly sure how to pose the question, so ask away if it is not clear:

Upon discovering several associated fossilized bones in a small area, how much do digging crews expand their search radius by to be reasonably certain that nothing is left behind? Is it e.g. a one foot radius around each bone? Two feet, five feet? Do they continue digging down or only horizontally? When do they know there is (likely) nothing else to find?

[Auspex]

It will be dependent on the nature of the deposit (was it a high-energy environment, or reworked, which would tend to scatter the bits), and on the potential scientific value of the bits recovered.

I have read about a T. rex dig that measured more than an acre!

[sseth]

Like Auspex indicated, some fossils may be scattered over a very large area, and others are completely articulated. I would always be on the side of more is better when it comes to fossils. I have found toe bones many dozen yards away from the majority of the skeleton, when looking for dinosaurs. Better to be safe than sorry.

[Auspex]

It also bears mentioning that the context of what was buried with the subject remains can be very important to understanding the paleoecology of the site.

In these cases, a large fine-toothed-combing may be called for.

[Troodon]

Well said by the others. Every situation is different and a digger friend of my who found Rex isolated bones which did not warrant excavation would go back to that area every year to see if mother nature helped in exposing additional bones.

Sometimes bones are not found articulated but in channel deposits or microsites. Here you can find all different types of species and one needs to follow the deposit to where it ends.

[Ridgehiker]

This is a really good question.

I have found over the years to be quite expansive in searching a site.

There are many variables of stratigraphy, deposition, etc. However, some of my best finds have been getting outside of expectations...looking where there likely isn't anything but...?

As Auspex mentions, we have Dino sites in Alberta that don't really end. An Albertosaurus bed in Dry Island is huge...a Centrasaurus bone be in another badlands area goes on for as long as someone wanted to excavate.

What's curious is the reverse. So often there is a productive fossil site...then nearby...nothing! Although everything about it seems identical...completely sterile. This is also the reason not to give up on an area. Nothing...nothing...nothing...then Bingo! I'm sure many of us have found good stuff where others have said it wasn't worth looking at.

Edited...Troodon just posted. Right now I'm sitting in Brooks, Alberta finishing a coffee before heading out to a couple areas beside Dinosaur Provincial Park. Doing what he said. Checking out a couple of productive sites....what has eroded out over winter?

Edited April 13, 2016 by Ridgehiker

[JimB88]

as far as whether to dig down or horizontally; most fossils occur on a horizon or plane in the rock. The exception being fossils that have weathered free of the matrix. So, generally speaking one would follow the layer or horizon the fossils occur on. This layer may not lay in a horizontal position as mountain building caused by continental collisions often tilt or fold the strata.

[Coco]

Hi,

A time I found a ray spine in a small layer very well preserved of falun. Usually we find little parts of ray spines there which don't exceed several centimeters long. I banged a little farther to brink out the spine and I didn't think that it would be so long, I broken it in the middle by knocking, it measured ... 17 cm ! (6" 7/10...). Always be careful !

Coco

[FossilDudeCO]

Fantastic question and even better answers thank you all!

[KansasFossilHunter]

I used to leave about one hammer length around a bone when I was making a slab or a jacket. Last year I was digging on what I assumed was an isolated Pteranodon wing bone. Partway through the trenching, I broke off a piece of rock and saw another bone sticking out! It turns out it was actually the scapulocoracoid which is pretty far removed from the distal wing bones. I just barely missed destroying it with my hammer. Now I'm WAY more careful when if comes to the bone horizon!

Just after I exposed the bone. You can see how the trench would have gone directly through the scapulocoracoid.

Lesson learned: Take the time to really clear an area before blindly trenching, it's always better to leave more room to work with later.

[KansasFossilHunter]

Everybody made it home safe

[jpc]

For me it depends onthe size of the bones/animal, the importance/excitingness of the specimen, the likelihood of finding more, and the amount of overburden. As others have said, every site is different.

Edited April 25, 2016 by jpc