EPIK’s Guide to Micro/Macro Sharks of the Central Texas Eagle Ford and Atco

[Mikrogeophagus]

Hey everyone!

 

Towards the end of my time down in Austin, I collected a dozen or so bags of matrix across three sites that covered the Bouldin Flags (Cenomanian), South Bosque (Turonian), and basal Atco (Coniacian) of Central Texas. Over the course of the last 6 months, I have processed and tried to identify everything that my sieve caught in order to complete this project of mine. I’m sure there are plenty of errors within this amateur study, but I hope that the overall information it provides will at least be of some use to my fellow hunters who are looking for a centralized place to figure out just what kind of tooth they stumbled upon in their local creek. I know that, especially in my first year of fossil hunting, the seemingly endless list of shark names looked like a mountain too tall to overcome. Perhaps this report might just help to demystify that obstacle. There were many expected finds and some total surprises. I learned a lot myself from this whole endeavor and am excited to share what I found.

 

Special shoutout to @Jackito and @LSCHNELLE for so kindfully sharing their fantastic sites as well as their expertise. This could not have been done without their help!

 

Also, if you have found a species of shark not mentioned in this report from the Bouldin Flags, South Bosque, or Atco of Central Texas, feel free to leave a reply with a photo and some info on your specimen!

 

Enjoy!

 

Abundant (), Common (), Uncommon (), Rare ()

 

Bouldin Flags (Cenomanian)

The Bouldin Flags represents the end of the Cenomanian stage of the WIS in Central Texas. It carries much of the typical “Woodbinian fauna” that is often associated with Cenomanian sites from across the continent. The formation is “flaggy”, tending to split into layers. Much of the formation can be devoid of vertebrate life, but now and then, extremely rich layers may crop up and yield an extensive diversity of sharks, bony fish, and even reptiles to collect from. Processing the matrix can be difficult. I tried to process only the softest material I could find from productive layers as the harder parts were sometimes almost solid pyrite or totally cemented into an unbreakable stone. Even the parts that are soft tend to carry lots of grit that are rough on the hands and fossils. Nevertheless, the Bouldin Flags has some of the most diverse shark and reptile fauna as well as the richest layers, making it well worth the effort of locating. 

 

The majority of the collecting for this formation was done in the Lower Bouldin Flags, however, specimens that also occurred in the limited Upper Bouldin Flags sampling will be marked with an asterisk (*=Upper BF)

 

 

Lamniformes

*Carcharias saskatchewanensis

 

Together with Cenocarcharias tenuiplicatus, these species make up the two most abundant sharks teeth to be found in the Bouldin Flags. They are typically only millimeters in size and tend to separate well from the matrix without breaking. C. saskatchewanensis can be easily differentiated from C. tenuiplicatus by its absence of fine striations on the labial faces of the cusps and cusplets. C. saskatchewanensis and C. tenuiplicatus are distinguished from Haimirichia amonensis by their significantly smaller size. I have also seen this species referred to as Microcarcharias saskatchewanensis.

 

*Cenocarcharias tenuiplicatus

 

A common tiny tooth found in the Bouldin Flags. They are easily identified by the presence of fine striations on the labial faces of their cusps/cusplets. Now and then, they may have an extra pair of cusplets.

 

Cretalamna catoxodon

 

Surprisingly rare given how abundant this genus usually is in other similarly aged strata of Texas. From the entirety of my material, I only came across one identifiable specimen in the final batch. Unlike mature Cretoxyrhina agassizensis, these teeth have a single pair of pointed cusplets and are usually more gracile. Unlike Cretodus semiplicatus, these teeth are more gracile and lack wrinkling on the base of the crown and cusplets. C. catoxodon is a relatively newly defined species within the genus Cretalamna and, to my knowledge, the only one documented from the Cenomanian. 

 

Cretodus semiplicatus

 

One of the most coveted shark fossils of the Eagle Ford is the fearsome Cretodus. These are some of the biggest and most robust teeth to be found and can be spotted quickly by their size and diagnostic wrinkled crown bases on both the labial and lingual faces. To my knowledge, C. crassidens does not appear until the Turonian. C. semiplicatus, unlike Cretodus houghtonorum, typically exhibits a U-shaped basal concavity and U-shaped crown base border whereas C. houghtonorum is more of a V-shape in both departments. Both typically have gracile cusps. In my hunting at the Bouldin Flags site, I found one perfect tooth and a single, large broken off cusp to another tooth. 

 

Cretomanta canadensis

 

This is one of the most interesting teeth to be had in the Bouldin Flags. Cretomanta has been interpreted as a planktivorous filter feeder. These teeth are sometimes confused with rostral denticles of Ptychotrygon triangularis, however the oral teeth of P. triangularis were not found at all in the Bouldin Flags Site. In contrast, the Atco Site (more on this later) did produce many of these oral teeth. I believe this suggests P. triangularis is likely not the culprit for the pictured specimens. Additionally, Cretomanta canadensis is commonly listed in faunas of other Cenomanian sites. Fairly recently in Northern Mexico, an amazingly preserved ray-like filter-feeding shark was discovered and named Aquilolamna milarcae. Sadly, no teeth were preserved, making it impossible to confirm synonymy between Aquilolamna and Cretomanta, but nevertheless there is a suspected connection between the two which future discoveries may one day prove.

 

*Cretoxyrhina agassizensis

On the right are the juvenile C. agassizensis ("Telodontaspis agassizensis")

 

Cretoxyrhina are always a welcome sight and not all that rare for the Bouldin Flags. These are some of the larger teeth to be had and are generally well preserved. They typically do not have cusplets, however some specimens may have poorly developed ones as Cenomanian Cretoxyrhina were still in the process of diminishing them. C. agassizensis is a chronospecies of the genus Cretoxyrhina, representing the time period of the Late Middle Cenomanian to the Early Middle Turonian. Throughout the sifting process, I came across small, thinly cusped and distally curved teeth that somewhat resembled the larger Cretoxyrhina teeth I had as well. In researching possible IDs for these teeth, I came across the species Telodontaspis agassizensis which seemed like a decent match. However, Siversson makes the point that this taxon seems to appear only in places where larger, more typical Cretoxyrhina specimens also occur. It would seem that the two genera are synonymous and these smaller teeth instead belong to juvenile C. agassizensis.

 

*Haimirichia amonensis

 

Medium-sized teeth that are extremely abundant in the Bouldin Flags as well as many other Cenomanian deposits of Texas. A decent degree of heterodonty exists and lateral teeth may have many pairs of cusplets. This species was previously known as Carcharias amonensis, however the discovery of a new and well preserved specimen showed that it possessed enough morphological differences to warrant the creation of the family Haimirichiidae. I originally misidentified these teeth as Scapanorhynchus raphiodon which appears to not exist in the Bouldin Flags.

 

*Squalicorax sp.

 

Squalicorax is one of the most abundant teeth present. They are easily identified by their unique shape that highlights their generalist diet. There is currently much work to be done in properly separating the species of this genus across the Mesozoic, so I will simply refer to all teeth found as Squalicorax sp.

 

 

Ptychodontiformes

*Ptychodus anonymous 

 

The most common Ptychodus teeth found in both the Bouldin Flags and South Bosque. P. anonymous can be distinguished from other co-occurring Ptychodus teeth most easily on the basis of having a defined marginal area where the transverse ridges will merge instead of bifurcating and running all the way to the end of the crown. P. anonymous is known to have two distinct morphotypes (Cenomanian vs. Turonian), both of which are represented in this post. The Cenomanian morphotype is common in the Bouldin Flags and are typically smaller and more robust than their Turonian counterparts (however my Turonian specimens are just as small as my Cenomanian ones). Another key difference in the morphotypes is that Turonian teeth have an apparent concentric ornamentation of the marginal area whereas Cenomanian teeth have no such feature. It is possible, in the future, these differences may lead to the creation of a new species between the morphotypes.

 

*Ptychodus decurrens

This larger specimen in the lower 3 photos was misidentified. I now believe it to be a P. decurrens from the Upper Bouldin Flags.

 

Ptychodus decurrens is a low crowned tooth that is also numerous in this formation. Like Ptychodus occidentalis, the transverse ridging gradually bifurcates to the edges of the crown as opposed to terminating at a distinct marginal area. These teeth are often broad and have the ability to get quite large in size.

 

The bottom specimen shown was originally misidentified as P. marginalis. I have taken another look and now realize P. decurrens is a stronger ID. Despite it being a fragment, I do not think the tooth shows signs of a concentric orientation of transverse ridges and instead seems to follow the hooked on one side and straight on the other ridge pattern more typical of larger P. decurrens. Also, I initially misidentified the formation the tooth came from as being South Bosque based on visuals alone. After getting the chance to process the matrix for micros, it shares much of the same microfauna with the Lower Bouldin Flags and has little faunal overlap with the South Bosque outcrop. I now believe the location to be Upper Bouldin Flags.

 

Ptychodus occidentalis

 

Ptychodus occidentalis is rarer in the Bouldin Flags than the other Ptychodus. They can be identified by the bifurcating nature of their ridges as they travel through the marginal area of the tooth to the edge of the crown. The crown height tends to be higher than that of Ptychodus decurrens. In comparison to P. anonymous, P. occidentalis generally possesses finer and more numerous transverse ridges. This species is also capable of producing some very large teeth. Ptychodus rhombodus is a smaller-toothed species that commonly occurs in the Cenomanian WIS that also shares bifurcating ridge features. It has been suggested, however, that these may represent a juvenile form of P. occidentalis.

 

 

Orectolobiformes

*Cantioscyllium decipiens

 

Common little teeth that belonged to a Mesozoic nurse shark. The teeth look similar to Chiloscyllium, but have striations present on the labial face.

 

 

Sclerorhynchiformes

*Onchopristis dunklei

 

Although not the rarest to find, Onchopristis dunklei represents an order of sharks that hardly seems to be found in the Bouldin Flags. This species tends to preserve both oral teeth and rostral teeth. The rostral teeth are quite iconic, being best known for the multiple barbs decorating its edge. These teeth are fragile and rarely collected in one piece. 

 

From the Lower Bouldin Flags, I collected a handful of oral teeth and broken rostral specimens. In my small sample of Upper Bouldin Flags material, I only collected one O. Dunklei rostral and it happened to be the single complete one in the collection.

 

 

Hybodontiformes
Indet. Hybodontiformes

 

Only a singular specimen of a Hybodontiformes tooth fragment was recovered. I don’t believe enough is present to make a confident determination as to whether it belongs to Meristodonoides or some other genera. It has striations on both sides of the tooth and a slight curvature.

 

 

Other Fauna

Amiid?

 

A single, tiny arrow shaped fish tooth was collected. It is difficult to confidently lay down an identification, but Amiid is a candidate for this morphology.

 

Coniasaurus crassidens

 

Coniasaurus crassidens may be found in the Bouldin Flags on rare occasion. Most commonly, teeth, jaw fragments, and vertebrae are found disarticulated amongst shark teeth and shells. Because of their position within the order Squamata, Coniasaurus vertebrae share many visual similarities with larger mosasaur vertebrae from younger strata such as the Ozan. Although Coniasaurus teeth exhibit heterodonty, most of their teeth have a characteristically bulbous shape that distinguishes them from all co-occurring sharks and fish (though anterior-most maxillary teeth may be quite gracile in contrast). While Coniasaurus seems to be restricted to the Cenomanian in England, American specimens cross the Cenomanian-Turonian oceanic anoxic event (OAE 2) and reach the Middle Turonian with some reports even further beyond.

 

Enchodus sp.

 

Typical of just about every Cretaceous exposure in Texas is the saber-toothed Enchodus. The Bouldin Flags is absolutely filled with them. The teeth are generally quite small and vary in shape. Most commonly, they are flattened and take on a recurved shape. Sometimes they may be conical and completely straight. They may be smooth or have striations.

 

Pachyrhizodus minimus

 

These are very small and resemble miniature mosasaur teeth. They are smooth around their circumference and have a strong distal curvature. Pachyrhizodus is a genus known for having relatively large heads, similar to modern Grouper fish.

 

Protosphyraena sp.

 

Protosphyraena was a genus of fish that heavily resembled modern swordfish. Their teeth are common finds all over Texas. They generally take on a flattened shape and bear two cutting edges. They can sometimes have a slight curvature or stay completely straight. The ones I collected were among the larger fish teeth found. 

 

 

Known but missing sharks

Pseudomegachasma comanchensis

Despite not having personally collected one, Pseudomegachasma comanchensis is known from the Bouldin Flags. Similar to Cretomanta, these sharks are suspected to have been the oldest elasmobranch planktivorous filter feeders. The lingual protuberances on these teeth are so large, they almost look like backwards root lobes.

 

Ptychodus marginalis

Ptychodus marginalis is better known from the South Bosque, but has been previously found in the Bouldin Flags, though it is on the rarer end as far as Ptychodus go. They can get large, sometimes to the size of a golf ball. P. marginalis is distinct from other Texan species of the genera in that its ridges go on to form concentric rings as they travel towards the edges of the crown.

 

 

 

Edited June 11, 2023 by EPIKLULSXDDDDD
Format

[Mikrogeophagus]

South Bosque (Turonian)

The South Bosque represents the Turonian portion of Central Texas’s Eagle Ford. Much of it is composed of tan mudstones that are very easily broken down using hot water and baking soda. Fishy material can be seen spread throughout the formation and shark teeth are sparingly dispersed amongst it. The best micro matrix occurs within hashy storm deposits. In terms of fauna, the South Bosque/Turonian changes substantially from the older Cenomanian in part due to the Oceanic Anoxic Event 2. This can be best seen in the further diversification of bony fishes which has been documented in this report and throughout the WIS during the period. For the newer fossil hunter, this formation is a more welcoming one and has the capacity to yield some beautiful and rare specimens intermingled with the more common. My personal favorites would have to be Ptychodus marginalis and Johnlongia parvidens both of which can be found with a little persistence.

 

Lamniformes

Cretoxyrhina mantelli

 

These are some of the larger teeth to be had and are generally well preserved. C. mantelli is a chronospecies of the genus Cretoxyrhina, representing the Late Middle Turonian and beyond. Cretoxyrhina lack developed cusplets, lack a nutrient groove, and are much larger than co-occurring Dallasiella willistoni.

 

Dallasiella willistoni

 

Compared to the Bouldin Flags, the teeth in the South Bosque do not get that small. In general, the smallest sizes are only just under a centimeter as opposed to a few millimeters. The species that makes up the majority of tiny teeth is Dallasiella willistoni. They have a single pair of cusplets, a nutrient groove, and generally a noticeable distal curvature. I initially thought I had a wider variety of sub-centimeter Lamniformes, but a closer inspection revealed it was all D. willistoni all along.

 

Johnlongia parvidens

 

Johnlongia parvidens is a special and rare tooth from the South Bosque. I managed to find several fragments as well as two relatively complete specimens. Johnlongia is considered to be within Odontaspididae and the visual similarities are readily apparent with other sharks of this family such as Carcharias saskatchewanensis. Though piscivorous, Johnlongia is suspected to be sister to Pseudomagechasma which can be found in the Bouldin Flags. J. parvidens can be differentiated from other teeth quickly by their extremely pronounced lingual protuberance. They usually have a tiny pair of cusplets, but these can be easily broken off while processing matrix.

 

Pseudoscapanorhynchus compressidens

 

Pseudoscapanorhynchus compressidens is a rare tooth that can be easily mistaken for Johnlongia parvidens. Compared with Johnlongia, Pseudoscapanorhynchus possesses wrinkling on the labial face, the lingual protuberance is thinner and not as pronounced, and the nutrient groove much less apparent. In the entirety of my searching, I only came across one identifiable specimen. I have seen this species also referred to as Protolamna compressidens in older papers.

 

Scapanorhynchus raphiodon 

 

No complete specimens were found, but fragments of the long, slender, and striated cusps occurred regularly. I am used to finding endless goblin shark teeth in the Campanian, but here they seem to be much less common.

 

Squalicorax sp. 

 

Squalicorax is one of the most abundant teeth present. They are easily identified by their unique shape that highlights their generalist diet. There is currently much work to be done in properly separating the species of this genus across the Mesozoic, so I will simply refer to all teeth found as Squalicorax sp.

 

 

Carcharhiniformes

Galeorhinus sp. 

 

During the Cenozoic, the generalist Carcharhiniformes came to replace the Lamniformes in their role as the dominant order of free-swimming sharks. In the Turonian, however, the Carcharhiniformes were still relatively tiny in both body size and percentage of the shark population. The genus Galeorhinus may have gotten its start close to the Cenomanian-Turonian boundary, making this specimen quite a special find in its close temporal proximity. Sadly, the root is completely missing, leaving only the main cusp and a few distal cusplets. It seems there are no other genera of shark from the time period to match this appearance and size, so I am fairly confident in this general identification. 

 

 

Ptychodontiformes

Ptychodus anonymous

 

The most common Ptychodus teeth found in both the Bouldin Flags and South Bosque. P. anonymous may be distinguished from co-occurring P. marginalis by lacking a concentric configuration of transverse ridges, having higher crowns, and being much smaller in overall size. P. anonymous is known to have two distinct morphotypes (Cenomanian vs. Turonian), both of which are represented in this post. The Cenomanian morphotype is common in the Bouldin Flags and are typically smaller and more robust than their Turonian counterparts (however my Turonian specimens are just as small as my Cenomanian ones). Another key difference in the morphotypes is that Turonian teeth have an apparent concentric ornamentation of the marginal area whereas Cenomanian teeth have no such feature. It is possible in the future these differences may lead to the creation of a new species between the morphotypes.

 

Ptychodus marginalis

 

Ptychodus marginalis is one of the most coveted teeth of the South Bosque. This formation tends to preserve them very well and in a way in which they can be easily cleaned of matrix. They can get large, sometimes to the size of a golf ball. P. marginalis is distinct from other Texan species of the genus in that its ridges go on to form concentric rings as they travel towards the edges of the crown.

 

Ptychodus whipplei

 

In North Texas, Ptychodus whipplei is a common find in the Kamp Ranch (Middle Turonian), however this species seems to not have that same abundance farther south until one reaches the Basal Atco (Early Coniacian). I hesitated on whether to even include this fragmented specimen because it is so poorly preserved, but its unique appearance compared to the usual P. anonymous and P. marginalis pushed me to at least take note of its occurrence. It seems to share a resemblance with images I’ve found online, but the identification remains weak. P. whipplei is known to have two distinct morphotypes from the Turonian and Coniacian. Generally, the Coniacian morphotype is larger which seems to be the case for the fragments in my collection.

 

 

Other Fauna

cf. Elopopsis sp.

 

Several examples of jaw fragments containing small, triangular, and longitudinally striated teeth were found. It is difficult to tell much from them, but the genus Elopopsis could be a match.

 

Enchodus sp.

 

Typical of just about every Cretaceous exposure in Texas is the saber-toothed Enchodus. The South Bosque is absolutely filled with them. The teeth are generally quite small and vary in shape. Most commonly, they are flattened and take on a recurved shape. Sometimes they may be conical and completely straight. They may be smooth or have striations.

 

Pachyrhizodus minimus

 

These are very small and resemble miniature mosasaur teeth. They are smooth around their circumference and have a strong distal curvature. Pachyrhizodus is a genus known for having relatively large heads, similar to modern Grouper fish.

 

Plethodid

 

Most fragments of fish bone from the South Bosque are totally unrecognizable, however the parasphenoid bones of Plethodid fish are very distinct. They are relatively flat and dark. One side is covered in tiny holes where small conical teeth were once attached for holding on to prey. Notable genera of Plethod fish include Pentanogmius the “sail fin fish” and Thryptodus the “battering-ram fish”. Part of me wonders if some specimens identified as small Pachyrhizodus minimus teeth may in fact be from Plethodids.

 

Protosphyraena sp.

 

Protosphyraena was a genus of fish that heavily resembled modern swordfish. Their teeth are common finds all over Texas. They generally take on a flattened shape and bear two cutting edges. They can sometimes have a slight curvature or stay completely straight. The ones I collected were among the larger fish teeth found. 

 

Pycnodont

 

One or more species of small Pycnodont fish are represented from the Turonian sample including teeth from multiple positions of the mouth. Much work needs to be done in defining and redefining the smaller genera that make up the Pycnodonts of the WIS. Gyrodus and Micropycnodon are two genera that I came across while researching the topic that could encompass the specimens found.

 

 

Known but missing sharks

Undescribed Ptychodus

Present in the South Bosque is a currently undescribed Ptychodus species that I did not come across. I will wait to post a description until after it is published.

 

Edited June 11, 2023 by EPIKLULSXDDDDD

[Mikrogeophagus]

Atco (Coniacian)

The Basal Atco is a thin chalk/marl that occurs at the bottom-most layer of the Austin Group. Up in DFW, it is filled with a diversity of jet black shark teeth. In Central Texas, the fossils take on more of a tan/reddish coloration and are often fragmented in my experience. Because it is limestone, I had to do a lot of processing with vinegar which is a bit of a pain. Thankfully, the formation at least comes with a fauna entirely unique to what lies underneath. In other words, it is worth exploring! I am going to skip marking the rarity of each species as coming across anything in the CenTex Atco seems to be an uncommon occurrence with the exception of unidentifiable teeth fragments and the occasional Ptychotrygon triangularis oral.

 

Lamniformes

Cretalamna sp. 

 

A single large Cretalamna specimen was obtained, but heavily fractured during processing. Unfortunately, I seem to have misplaced this tooth, but I at least managed to get a photo of it before the disappearance. Only off of the picture, I think upper lateroposterior Cretalamna is the closest match. It was quite a robust tooth and the most complete larger specimen I found in the Atco.

 

Pseudocorax laevis 

 

Pseudocorax laevis are smaller and resemble the general shape of Squalicorax sp. They can be differentiated by their lack of serrations and the presence of a nutrient groove. It has been suggested that P. laevis and Pseudocorax granti are synonymous.

 

Scapanorhynchus raphiodon

 

No complete specimens were found, but fragments of the long, slender, and striated cusps occurred regularly. I am used to finding endless goblin shark teeth in the Campanian, but here they seem to be much less common.

 

Squalicorax sp.

 

Squalicorax is one of the most abundant teeth present. They are easily identified by their unique shape that highlights their generalist diet. There is currently much work to be done in properly separating the species of this genus across the Mesozoic, so I will simply refer to all teeth found as Squalicorax sp. Unlike Pseudocorax, Squalicorax are serrated.

 

Orectolobiformes

Chiloscyllium greenei

 

Chiloscyllium is a genus of shark still around today, commonly known as the Bamboo Shark. Their teeth are quite small and share a resemblance with Cantioscyllium. Whereas Cantioscyllium has distinct striations on the labial face of the tooth, Chiloscyllium is completely smooth.

 

Ptychodontiformes

Ptychodus atcoensis

 

Ptychodus atcoensis, as its name suggests, was originally found in the Atco. It is a rarer species and one of the newer ones to be named. The most iconic feature of P. atcoensis is the “chevron” pattern taken on by the transverse ridges.

 

Ptychodus mortoni

 

An easy to spot species due to its radiating ridges. Ptychodus mortoni first appears in the Coniacian and quickly becomes a dominant species throughout and into the Santonian. 

 

Ptychodus whipplei

 

The most common Ptychodus species of the Austin Atco. These teeth are readily identifiable by their extreme crown height. P. whipplei is known to have two distinct morphotypes from the Turonian and Coniacian. The Coniacian morphotype is likely what is present in the Atco, however the P. whipplei specimens collected were too fragmented/corroded to make that determination. Generally, the Coniacian morphotype is larger which seems to be the case for the fragments in my collection.

 

Sclerorhynchiformes

Ischyrhiza schneideri

 

These strange denticles/teeth are difficult to define. Hamm’s Atco paper identifies them as Ischyrhiza schneideri rostral teeth, but notably no oral teeth of this species were associated with them (not to say they don’t exist or haven’t been documented elsewhere). Similar specimens to what I have pictured often co-occur with Ptychotrygon, however there is no definitive evidence that they belong to the genus (or direct evidence of rostral teeth being present in Ptychotrygon altogether). Many have identified these structures as dermal denticles rather than rostral spines which adds another layer of complexity to the discussion.

 

Ptychotrygon triangularis

 

Ptychotrygon triangularis oral teeth are unique amongst the Sclerorhynchiformes for their prominent transverse ridges (“ptycho” meaning “fold” in Greek). Of all the shark material from this layer, P. triangularis was by far the most common. Since the creation of the genus, the lack of definitive rostral teeth for P. triangularis has been a topic for hot debate. Being within the suborder Sclerorhynchoidei, it would appear logical to assume that Ptychotrygon should have rostral teeth as do all the other genera within the grouping. However, a series of recent and groundbreaking Turonian Ptychotrygon skeletal discoveries from Morocco showed no evidence of rostral teeth, lending support for the idea that the genus lost this feature. That being said, this absence may not necessarily be genus-wide and historically there have been many supposed rostral denticles associated with Ptychotrygon.

 

Sclerorhynchus cf. S. priscus

 

Hamm reports Sclerorhynchus cf. S. priscus from the Atco of North Texas in specimens that are similar to what I found in Austin. Only rostral teeth were collected, so there is limited confidence in distinguishing these from other species like Sclerorhynchus atavus.

 

Texatrygon hooveri

 

Relatively smooth cuspidate teeth that bear resemblance with Ptychotrygon, however they have no transverse ridges. Relative to P. triangularis, these teeth are much rarer in the Atco. 

 

Other Fauna

Enchodus sp.

 

Typical of just about every Cretaceous exposure in Texas is the saber-toothed Enchodus. The Atco is absolutely filled with them. The teeth are generally quite small and vary in shape. Most commonly, they are flattened and take on a recurved shape. Sometimes they may be conical and completely straight. They may be smooth or have striations.

 

Pycnodont

 

One or more species of small Pycnodont fish are represented from the Coniacian sample including teeth from multiple positions of the mouth. Much work needs to be done in defining and redefining the smaller genera that make up the Pycnodonts of the WIS. Gyrodus and Micropycnodon are two genera that I came across while researching the topic that could encompass the specimens found. In particular, some molariform teeth had crenulate ornamentation typical for Micropycnodon kansasensis, making it a top candidate identification.

 

Indeterminate Fish

 

A couple of fish teeth that I have difficulty drawing any conclusions on.

 

Known but missing sharks

Ptychodus latissimus

A highly sought after and rarer species of Ptychodus found in the Lower Coniacian. This tooth is low crowned and unique in having fewer, yet thicker transverse ridges that abruptly end at the marginal area.

Edited June 11, 2023 by EPIKLULSXDDDDD

[grandpa]

Thanks so much for this great guide. 

 

1 hour ago, EPIKLULSXDDDDD said:

Towards the end of my time down in Austin

Are we losing you to another area?

[Notidanodon]

Brilliant guide, on the galeorhinus, is galeocorax in the time frame of that site?

[old bones]

Terrific guide! This will be a very useful reference, thank you.

[Mikrogeophagus]

9 hours ago, grandpa said:

Are we losing you to another area?

I had my last semester of college in the fall so I have since moved back to DFW. Soon I will be moving down to San Antonio where I'll live for at least the next four years! San Antonio is a bit intimidating in the fossil realm, but I look forward to the challenge and the opportunity of exploring a new side of Texas.

[Mikrogeophagus]

8 hours ago, Notidanodon said:

Brilliant guide, on the galeorhinus, is galeocorax in the time frame of that site?

I haven't actually heard of Galeocorax so thank you for bringing it to my attention. The site is Middle Turonian and it seems Galeocorax was present in the Turonian so it is possible...

[ClearLake]

 Very nice guide, I have not done that much shark tooth collecting in central Texas, but this will be handy nonetheless. 

[Notidanodon]

3 hours ago, EPIKLULSXDDDDD said:

I haven't actually heard of Galeocorax so thank you for bringing it to my attention. The site is Middle Turonian and it seems Galeocorax was present in the Turonian so it is possible...

yeah they're not common, that one from my collection is one of only two ive seen  

[grandpa]

3 hours ago, EPIKLULSXDDDDD said:

I had my last semester of college in the fall

Congratulations! 

 

3 hours ago, EPIKLULSXDDDDD said:

Soon I will be moving down to San Antonio where I'll live for at least the next four years!

Oh, good.  So you will at least be close! 

 

Graduate school in S.A.?

[Mikrogeophagus]

1 hour ago, grandpa said:

Graduate school in S.A.

Doing dental which is kinda fossil related but also isn't . Not too far from Austin, so I'll definitely be in the area now and then!

[Jared C]

useful for texas hunters everywhere, this guide is spectacular, bravo

[LSCHNELLE]

Thanks EPIK. I learned something new about Cretoxyrhina species and about Pachyrhizodus species from your report! Hope things are well with your San Antonio educational work. My Ptychodus hunting experience in Central Texas Basal Atco was biased by a heavy concentration of Ptychodus mortoni at one location. So, they were more common for me in the Lower Coniacian than Ptychodus whipplei. The score is currently 190 P. mortoni vs 10 P. whipplei. Based on my experience, Ptychodus mammillaris is probably the rarest in Central Texas. I have only identified 5 out of 1400 Ptychodus teeth. Also, I found a partial Thryptodus skull in the Upper Bouldin Flags Member.

[Jared C]

3 hours ago, LSCHNELLE said:

Also, I found a partial Thryptodus skull in the Upper Bouldin Flags Member

any photos? I don't think I'm alone when I say I would love to see  

[LSCHNELLE]

I am thinking that it was a rostrum. Not sure if that is the right term. After gluing it together from three or four pieces, I gave it away to Shawn Hamm to donate to a researcher. But, here is a photo of the three or four separate pieces (circled in red). Another photo find is of a larger "bumper" piece, I found later at the same location. I think it is a Thryptodus.

[Mikrogeophagus]

@LSCHNELLE Glad you liked the guide and nice finds there yourself! I plan on making one for N TX but it'll take a long time. I'll have to swing by Austin some time once this drought ends!

[Jared C]

35 minutes ago, LSCHNELLE said:

I am thinking that it was a rostrum. Not sure if that is the right term. After gluing it together from three or four pieces, I gave it away to Shawn Hamm to donate to a researcher. But, here is a photo of the three or four separate pieces (circled in red). Another photo find is of a larger "bumper" piece, I found later at the same location. I think it is a Thryptodus.

i agree! Looking at pictures it looks like a match, Prior to your ID I've never heard of that taxon but believe I have a Thryptodus rostrum from the bouldin flags as well. Very cool!

[erose]

This is excellent. I have a large amount of Eagle Ford from the former Terra Vista site in Round Rock.  I have finally, years later, started on identifications and cataloging.

 

I believe a large portion is South Bosque.

 

Lee has helped me on occasion  but. ranges  it still confuses me