Author: Sam Ocon

Visiting Penn Dixie Fossil Park

by @nathan-newell

 

My family and I vacationed at Niagara Falls last summer (2019), and whenever I go on vacation I like to snoop around Google for paleontology-related attractions. I was excited to discover that the Penn Dixie Fossil Park (https://penndixie.org/) was only a 40-minute drive from Niagara on the New York side. Fortunately, I found the site a few months ahead of the trip so I had enough time to convince my wife to take a day away from the spectacular falls to grub around in the dirt. 

 

Penn Dixie is a nature preserve in Blasdell, NY, a few minutes south of Buffalo. It’s a Devonian site from the Moscow Formation, a former quarry that’s been dedicated to fossil hunting. The Penn Dixie website boasts of brachiopods, horn corals, crinoids, and most excitingly for me, trilobites! There are so many fossils here that they literally bulldoze a layer every once in a while to freshen the fossil piles. This seemed ridiculous to me, considering fossil hunting in the Virginias consists of me schlepping around road cuts having rare “wow” moments whenever I happen upon random trilobite pieces. And finding cephalons (heads) with eyes is even more difficult.

 

mFeM 61072

When we got there, a guide gave us a very interesting tour with plenty of good tips, which unfortunately, I couldn’t pay much attention to since I was in such close proximity to trilobites just waiting to be found! I got to work as soon as I could, pinballing from this pile to that, looking for the coolest trilobites possible. I didn’t see any museum-quality specimens but I did see lots of pygidiums (tails), thoraxes, and even cephalons with eyes! There were even a good deal of brachiopods and horn corals. Every once in a while, I’ll call back to my wife and kids, exclaiming how great the fossils collecting here was. This is nothing like normal fossil collecting, so don’t get spoiled! 

 

mFeM 60331

Meanwhile, they had just plopped down at a random spot and sifted through rubble nearby. But hey, not everybody can be a paleo-pro like me, right? After about 15 minutes of me sprinting from pile to pile, I sprang back to my wife to show her the goods. She held something up. “Is this a good one?” It was; in fact, it was much nicer than any brachiopod I have ever found. My kids had similar luck, finding some amazing specimens, many of them better than mine. Thus, I learned an important lesson: whenever I go to a fossil site now, I try to just “plop down at a random spot” for a while and see what I find before I start scurrying around.

mFeM60191

Overall, I had great luck finding specimens that are really spectacular, at least compared to what I usually find. If you scroll through my fossil specimens from Blasdell, NY, you will see my specimens from Penn Dixie. And I was sure to give credit where due!

mFeM60191

If mFeM 60191 turns out to be a new species or variety somehow, I’ll name it after my wife. She earned it!

A quick and dirty guide to the general identification of fossil shark teeth

by @bill-heim

 

INTRODUCTION

This will be a quick guide to the identification of most teeth down to the level of order.  Below this, at the family, genus and species level, there are many published guides both in book form and on the internet that will help in this area.  This will cover most of the larger types which are most likely to be collected.  I will omit (for space reasons) the smaller types such as Orectolobiformes (Nurse and Carpet Sharks), Heterodontiformes (Port Jackson Sharks), Pristiophorifomes (Saw Sharks), Squaliformes (Dogfish), Squatiniformes (Angel Sharks) and older, more primitive sharks such as Hybodontiformes.  Most of these omitted types are small, rare, and/or confined to specific areas or ages and thus somewhat less likely to be collected.

Note: For sharks, Order names end in ‘iformes’, Family names end in ‘idae’. Genus names often end in ‘us’ but don’t have to.  Species names vary widely. Genus and species names are italicized. Genus is capitalized, species is not.

White Tip Reef Shark

We will briefly cover the Orders of Carcharhiniformes (Grey Sharks), Hexanchiformes (6 and 7 Gill Sharks), and Lamniformes (Giant Sharks, Makos and their relatives, and Sand Tiger Sharks).  The teeth of these various animals are usually fairly large and most often collected.

The first question to ask is what age is the tooth?  Genera and species are usually confined to a certain age frame.  Knowing that age range limits the possible identifications.

 

KEY ROOT FEATURES 

When one collects a specimen, they usually focus on the enamel blade.  As this is harder and more durable than the root, it usually survives damage and wear better than the root.  However, the root often contains details that can narrow the identification down to genus and/or species level.

Details to look for on the root are:  Is there a nutritive groove in the center of the root? This would be found on Carcharhiniformes, as with the Sandbar shark, Carcharhinus (Figure 1) and some Lamniform sharks such as the Sand Tiger Sharks here illustrated by Carcharias (Figure 2) and their relatives, along with the Porbeagle Sharks.

Figure 1. Carcharhinus tooth displaying nutritive root

Figure 2. Carcharias tooth displaying nutritive root

Are there central pore(s) as with Makos, Isurus (Figure 3); and Great Whites, Carcharodon (Figure 4)?

Figure 3. Isurus tooth displaying central pore

Figure 4. Carcharodon tooth displaying central pore

Are there scattered pores across the root as found in Crow Sharks, Squalicorax (Figure 5.); Giant Sharks, i.e. Carcharocles (Figure 6) and its ancestors; the Hexanchiform sharks, such as the Six Gill, Hexanchus (Figure 7); and the Seven Gill Shark, Notorynchus (Figure 8)?

Figure 5. Squalicorax tooth displaying scattered pores	Figure 6. Carcharocles tooth displaying scattered pores
Figure 7. Hexanchus tooth displaying scattered pores	Figure 8. Notorynchus tooth displaying scattered pores. Note: the lower teeth, illustrated here, differ by the number of cusps, lower six gill teeth have more than seven cusps, upper teeth of both species have less cusps.

Other important features can be found on the shoulders of the root. Are there lateral cusplets as with the aforementioned Sand Tigers, or as seen here in Otodus (megalodon ancestor, Figure 9)?

Figure 9. Otodus tooth displaying lateral cusplets.  Note: There is no nutritive groove in the root.

Are there serrations on the shoulders as seen here in a tiger shark, Galeocerdo?

Figure 10. Galeocerdo tooth displaying serrated shoulders. Note: a shallow nutritive groove is present which helps put it in the order Carcharhiniformes.

 All these various shoulder features are easily damaged which is why it is important to have excellent quality specimens for positive identification.

 

KEY BLADE FEATURES

Moving on to the main cusp or blade, we can further narrow down the identification.  Keep in mind that the flat side of the tooth faces the outside of the mouth (labial) while the curved, more attractive side faces the inside of the mouth (lingual). 

The first question, is it serrated or smooth edged?  There are various serrated teeth existing at different times.  In the Cretaceous, if the tooth is serrated it usually a species of Squalicorax (Figure 11), or more rarely, Pseudocorax. 

Figure 11. Squalicorax tooth displaying a serrated blade.

In the Palaeocene, the only serrated tooth is Palaeocarcharodon (Figure 12).

Figure 12. Palaeocarcharodon tooth displaying a serrated blade.

In later epochs, we add the various Carcharhiniformes, including the family of Hemigaleidae, such as Hemipristis (Figure 13), along with some of the aforementioned Laminformes, Carcharodon* (Great White) and Carcharocles (Giant Shark).  There are a few others, but they are rare.

Figure 13. Hemipristis tooth displaying a serrated blade.

*Note: Most fossil species of Carcharodon are not serrated.

 

FURTHER IDENTIFICATION

Once you have narrowed down the order that the tooth is found in, you can then begin getting the identification down to family and then genus and species. Published guides can help you here. In addition I have been slowly publishing identification guides in the Group -Shocking Shark Teeth- which can be found here: https://www.myfossil.org/groups/shocking-shark-teeth/ 

You may have to dig down to older posts to find all of them. Perhaps in the future these posts can be consolidated into a single guide.