Strange Holes on Petrified Wood Bark from the Mid-Late Eocene of Texas

[Ramon]

Hello,

I found this piece of petrified wood last month. It comes from Middle Eocene (37-35 million years old) terrestrial sediments, from the Yegua Formation of eastern Texas.

What I love about this piece, is that it is a piece from the bark of the tree. The tree that this specimen belonged to, was some kind of hardwood species (angiosperm), probably something like maple or birch, judging by the structure of the wood in one of the endcuts/endgrains.

What is so special about this piece, is that the bark side is covered in some sort of carbon film material, which gives it a nice, dark brown-black coloration. 

What is also very intriguing about this specimen, is that it has a couple of oval, conical shaped holes. They have a diameter of 5-6 millimeters, and a depth of 3-5 millimeters.
At first, I thought these were the egg niches of cerambycid beetles. But they don’t quite match the shape of beetle egg niches, or other insects burrows that I’ve seen online. The egg niches of beetles have a slit at the bottom of the dent. They are also shallower than the dents in my piece of petrified wood, and are almost never arranged in a way, that is parallel to the wood.

Now, I’m starting to think that they might be feeding holes, done by a woodpecker while foraging for food.

From the information I’ve seen online, and the pictures that I’ve seen, they very closely resemble the holes in my piece of wood.

Foraging holes done by woodpeckers are elongated, and cone-shaped (meaning that they narrow out into a point at the bottom of the hole. They are often aligned parallel to the direction of the trunk, and have a more neatly arranged orientation, than insect burrows/borings.

The holes in my specimen meet all of those characteristics. They size is also what you would expect from woodpecker foraging holes.

 

Here is the specimen

 

Here I’ve highlighted the holes in the specimen

 

Here are some close-ups of some of the holes.

(Notice how they narrow down to the bottom, which is a characteristic of woodpecker foraging holes.)

 

I wanted to know what you guys think of this. 

[Ramon]

Here, I have attached some pictures of modern woodpecker foraging holes that I got from the web.

Notice how they also taper down towards the bottom.

[JohnJ]

Nice piece of fossil wood!  To me, this looks just like where a small branch rotted out of the main trunk prior to mineralization.  I think damage from any Eocene critter would be much more random and counter to the wood grain.

[Rockwood]

Agreed. That is just what the inside end of a branch looks like. They tend to survive a bit longer than the remaining wood as the trunk rots away, making them quite visible many times.

[Ramon]

14 minutes ago, JohnJ said:

Nice piece of fossil wood!  To me, this looks just like where a small branch rotted out of the main trunk prior to mineralization.  I think damage from any Eocene critter would be much more random and counter to the wood grain.

 

4 minutes ago, Rockwood said:

Agreed. That is just what the inside end of a branch looks like. They tend to survive a bit longer than the remaining wood as the trunk rots away, making them quite visible many times.

Thanks for the quick responses!!

 

I think that would explain the lack of randomness in the holes. 

However, this seems to have been a part of the main trunk of the tree, or at the very least from one of the very large branches of the tree. I don’t think the branches would have been that small in that part of the tree.

I also don’t see how they would hollow out into a conical shape that narrows down towards the bottom, and always in a consistent shape.

[Rockwood]

19 minutes ago, Ramon said:

 

Thanks for the quick responses!!

 

I think that would explain the lack of randomness in the holes. 

However, this seems to have been a part of the main trunk of the tree, or at the very least from one of the very large branches of the tree. I don’t think the branches would have been that small in that part of the tree.

I also don’t see how they would hollow out into a conical shape that narrows down towards the bottom, and always in a consistent shape.

A tree is essentially many trees concentrically stacked. Even the largest branches started as a tiny bud. That is the inside point of each cone shaped structure. The cone gets bigger as the branch expands in diameter. The branch stays at the same point on the trunk.

[Thomas.Dodson]

I agree with the others. In addition to what Rockwood mentioned also look up Backbudding as one possible reason for smaller branches on the main trunk. It is a response in trees to pruning (or damage) where dormant buds away from the damaged area become active, often on the trunk of a tree.

 

As Rockwood mentioned the base tends to survive a bit longer than the remaining wood as it rots away. Also, as broken branches heal over they also form scars over the base of the same general shape and form. Look up woodworking knots. These remain underneath even after healing and the knots and scars show up in fossils as do the branch bases. See the attached photo for a (large) example of a healing branch scar on a 120 lb stump I have.

[Caverat]

I'd like to share images of some Cretaceous petrified wood from southeast Missouri that displays various wood damage effects, boring and, I believe healed branches. A polished end shows the effects through the annual rings. The light blue grid is one inch. Sorry, too many MB, I'll have to post the exterior view later....

Edited December 17, 2020 by Caverat
Explained I will add an exterior image later due to size

[LabRatKing]

Boy, sure is a lot of petrified wood with branch knots showing up this week!

[Rockwood]

9 minutes ago, Caverat said:

I believe healed branches.

With you on this part. The tree often gets on with business after limbs have been shaded out and die.

I don't see significant other damage though. I think it was just growing in a well light area at the time allowing many secondary buds to develop into a bushy looking tree.

[Ramon]

11 minutes ago, Caverat said:

I'd like to share images of some Cretaceous petrified wood from southeast Missouri that displays various wood damage effects, boring and, I believe healed branches. A polished end shows the effects through the annual rings. The light blue grid is one inch. Sorry, too many MB, I'll have to post the exterior view later....

That polished cross section looks beautiful 

I wonder what species of hardwood tree it’s from. It somewhat resembles oak (Quercus).

[Mahnmut]

Hi,

interesting piece.

I first thought the holes break the wood grain, indicating damage. But at least some of the lines "detour" around the holes, best visible in your last closeup picture. That is a strong argument for something related to the trees growth. Would be interesting to find out more about the species. We are used to trees growing big branches from the trunk and smaller ones from those,then twigs, leaves, flowers... but as has been mentioned before, there are circumstances when a tree starts growing new shoots from main branches. There are also species that do this as their normal growth pattern.

In cocoa for example the flowers and fruit do grow directly from the main trunks, it is called cauliflory.

Best Regards,

J

[Caverat]

2 hours ago, Mahnmut said:

Hi,

interesting piece.

I first thought the holes break the wood grain, indicating damage. But at least some of the lines "detour" around the holes, best visible in your last closeup picture. That is a strong argument for something related to the trees growth. Would be interesting to find out more about the species. We are used to trees growing big branches from the trunk and smaller ones from those,then twigs, leaves, flowers... but as has been mentioned before, there are circumstances when a tree starts growing new shoots from main branches. There are also species that do this as their normal growth pattern.

In cocoa for example the flowers and fruit do grow directly from the main trunks, it is called cauliflory.

Best Regards,

J

Thanks! Unfortunately, I am not qualified to identify the species, but would be happy to work with someone who can. This piece is a small portion of a number of logs that were exposed when I-55 was being constructed in southeast Missouri through Crowley's Ridge (a Cretaceous deposit). The project foreman had a half cord of petrified logs piled up by his trailer and let me know to come get some. I wish I'd taken more... Here is the exterior image I promised. As you can see, it has three small dimples, presumable former twigs.

[Ramon]

5 hours ago, Caverat said:

Thanks! Unfortunately, I am not qualified to identify the species, but would be happy to work with someone who can. This piece is a small portion of a number of logs that were exposed when I-55 was being constructed in southeast Missouri through Crowley's Ridge (a Cretaceous deposit). The project foreman had a half cord of petrified logs piled up by his trailer and let me know to come get some. I wish I'd taken more... Here is the exterior image I promised. As you can see, it has three small dimples, presumable former twigs.

Those look very much like the ones in my piece.
Thank you all so much for helping to identify them 

[Mark Kmiecik]

18 hours ago, Ramon said:

However, this seems to have been a part of the main trunk of the tree, or at the very least from one of the very large branches of the tree. I don’t think the branches would have been that small in that part of the tree.

How big is the trunk of a tree one week after the seed sprouts? How big is the biggest branch in one month? They all start out the size of toothpicks and grow larger if nothing prevents it. Here's the mighty oak: