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Consolidated all my informational Topics to make it easier to reference. Will keep updating since some of the reference material is outdated. Have to thank @PFOOLEY for suggesting this consolidation and it makes it a lot easier for me to access these topics as well as our members to know what's out there. General Tips in Buying Theropod Teeth Dinosaur Anatomy 101 Stratigraphy of the Late Cretaceous in North America Best Books for Dinosaur Identification Rare Theropod Teeth (World Wide) Identification of Some rarer Theropod Teeth Triassic Identification of Dinosaur Teeth from the Triassic of New Mexico Jurassic: Morisson Formation Identification of Theropod Teeth Quick Guide To Sauropod Teeth Tips in Buying a Sauropod Foot Claw Ornithischians from the Morisson Formation Jurassic: Europe Dinosaurs of Costal Portugal Jurassic Theropods of Germany Cretaceous: USA Hell Creek & Lance Formation Fanual List Identification of Theropod Teeth in the Hell Creek and Lance Formations Identification of Troodontid Teeth Identification of Tyrannosaurid Teeth From USA & Canada Identification of Ankylosaurid Teeth Identification of Acheroraptor Teeth Identification of Hadrosaur Teeth Identification of Claws and Ungals from the Hell Creek and Lance Formations Identification of Pachycephalosaurid and Thescelosaurus Teeth Tooth Features in Tyrannosaurids The Case for Nannotyrannus Dakotaraptor Teeth and Claws Hell Creek Fm Identification of Bones /Claws from Alvarezsaurids from North America Hell Creek Faunal Representation Identification of Theropod Teeth from Judith River Formation ( Campanian ) Includes Faunal List Fanual List from the Two Medicine Formations . Theropod Assemblage of New Jersey Cretaceous: Kem Kem of Morocco Kem Kem Theropod Teeth Kem Kem Theropod Tooth Morphology Identification of Sauropod Teeth from the Kem Kem Tips in Purchasing a Spinosaurid Hand Claw Identification of Claws from the Kem Kem Identification of Spinosaurid Jaws from the Kem Kem Guide to Help Purchase Rooted Moroccan Theropod Teeth Pterosaur Teeth from Kem Kem Republic of Niger Identification of Theropod Teeth Thailand Identification of Spinosaurid Teeth Cretaceous: South America Patagonia's Theropod Teeth Cretaceous: Uzbekistan: Identification of Theropod Teeth: Uzbekistan Sauropod Teeth: Uzbekistan Cretaceous: Europe Identifying Baryonyx Teeth

This is now my third post on my finds from last years trip to Wyoming. If you want to check out my previous posts click on these links - Theropod claw and Microsite Fossil ID. (* = two specimens of similar size) 1. Brachychampsa montana tooth (1 cm). 2. Thescelosaurus neglectus vertebra (2.5 cm). 3. Lonchidion selachos (?) Hybodont spine (3.5 cm).

Last summer on my trip out west, I found these teeth at a Lance Formation microsite in Wyoming. Many of the fossils were found through splitting a yellowish-orange concretion filled matrix, while others were free from it. This site was on the same ranch where I found my theropod hand claw but in separate locality. It's rather late (EST) at the time I'm posting this but wanted to show some of the teeth I found and was hoping I could get some help identifying them. 1. Pectinodon bakkeri 2. Richardoestesia sp. (?) 3. Lizard/ Worn Herbivorous Dinosaur Tooth (?)

Before I go back out west to the badlands of Wyoming in July, I thought I should post some pictures of one of my best finds from last years trip; My theropod hand claw (Nanotyrannus/ Juvenile T. Rex?). Hope you enjoy!

I’m probably posting this in the wrong topic area. I’m not sure which it goes in. This link is from my alma mater. I’ve posted the link before. https://fossil.swau.edu/ It’s to their fossil database. Many of the fossils have a 3D viewer option where you can look at the fossil 360 degrees. I saw this Trodon tooth on there this evening and thought it was pretty cool looking. I can’t recall ever seeing a Trodon tooth on here before so I thought I’d share the link. It came from the Lance Formation in Wyoming. I’ve been on the dig a couple times. I can’t get the link to go directly to the tooth so you can view it 360, but if you click on the browse tab after you go to the link then type in the catalog # HRS06576 it will take you to it. There are over 20,000 fossils on there from the Lance formation. I saw lots of teeth on there. Some from species I’d never heard of before. This is another Trodon tooth I saw on there. I think it’s very cool looking. I forgot to crop my screenshot. Oops.

Not sure how many have see this Devian Art Representation of the Dinosaur fauna in the Hell Creek & Lance Formations. It's Paleop interpretation of what he believes exists. Download the image in the link to see it best. Not everything he shows has been officially described but the number and type look pretty good. It's pretty cool The image is the link

Troodontids certainly are one of my favorite dinosaur families. Intelligent and what a set of chompers to eat you with, all you can ask for in a cool dinosaur. Will start this with the Pectinodon teeth in my collection and will continue to add as I take photos. This species has some of the coolest teeth. Pectinodon bakkeri is the only named Troodontid in the Hell Creek and Lance Formations. This is a tooth taxon and its teeth are significantly much smaller than its big cousin Troodon formosus. Lance Formation Hell Creek Formation A couple of the teeth in matrix are partially rooted which is extremely rare since the teeth are so small Hell Creek Formation - Powder River County Hell Creek Formation

Only two Ankylosaurs are reported from the Hell Creek and Lance Formation the Nodosaurid Denversaurus schlessmani and Ankylosaurid Ankylosaurus magniventris. I've identified my material to reflect these dinosaurs and if additional ones are discovered will change my identification. Material from these dinosaurs are extremely difficult to find with Teeth and Scutes being the most common. Bones are extremely rare. My Tail Club - also have a container full of isolated pieces that go to the missing portion. A few representative scutes from my collection. Most come from one area and are most likely associated. Have +30 from this site. One of my dinner plate scutes I call this my Bactrian Camel double humped scute. Different locality with a bulbous base.

A member asked me to check out some auction offerings for Morrocan Dromaeosaurus teeth and I did and they of course they were improperly identified. Not being familiar with the identification of these teeth I tried to help him by checking around on different dealer websites and was appalled at what I found. What I refer to as key dinosaur suppliers, on the web, were selling Dromaeosaurus teeth from the Hell Creek Formation of Montana. What makes me more upset is that I told one of them that they do not exist. All the listings were beautiful teeth however they were not Dromaeosaurus but looked like Nanotyrannus. Reminder to all those that are interested in purchasing teeth or bones from the species Dromaeosaurus it does not exist in the Hell Creek Formation or Lance Formation or Morocco. That species can only be found in the States from the campanian deposits of the Judith River Formation and Two Medicine Formation of Montana. Canada also has a number of formations where it can be found also in Campanian deposits but you rarely see them offered for sale. The Hell Creek and Lance Formations have only two Dromaeosaurids described Acheroraptor and Dakotaraptor. So if your interested in purchasing a Dromaeosaurid tooth from those faunas it needs to be from one of those dinosaurs. Since domestic Dinosaur dealers don't seem to have their act together I suggest that you post any interest in these type of teeth here on the forum before you buy to be sure its properly identified.

Bird and Pterosaur material is extremely rare in the Hell Creek and Lance Formations. Over the years I've purchased and found a few bones that I believe fit this category but not certain. Some may be mammal or reptilian. I'm not a bird guy so if you see something that does not seem right please let me know. Not a lot is published so I'm always open to learning. I showed this to a well respected theropod paleontologist and the potential ID's were his thoughts Aviasaurus sp. ID : Hxmendoza

I can't really tell if this had a single or double root. Cool shed tooth either way. The seller said it's from the Lance Formation, near Newcastle, Wyoming.

In going through some matrix from the Lance Formation, Late Maastrichtian, Wyoming, which shares much fauna with the Hell Creek formation, I have found even more interesting things since my last posting on this area. 1. The first I believe is a theropod, similar to the one in my previous posting, although slightly larger. 2. Is this (unknown 11) also a theropod tooth, or maybe crocodillian? 3. Is unknown 10 a pycnodont fish tooth? 4. Unknown looks like what has been identified as a ceratopsian "spitter" tooth in a previous posting, but this seems awfully small. 5. I have no idea as to what unknown 9 is. It looks like a tiny jaw with teeth, but seems to be closed off on both ends. I tried to clean it more, but was afraid of breaking it - it's only 2mm. 6. Unknown 6 looks like some tiny amphibian (maybe Newts) teeth that I have seen from the Permian, but not sure. 7. Unknown 7 also reminds me of ceratopsian teeth, but once again, this is really small and flatter. The hash marks are 1mm. Thanks for any help.

Hi guys, On a auction website I bought a collection of small Dinosaur/ Mammal fossils from the Lance Formation in Wyoming. First photo: Have you any idea which teeth belong to what dinosaur or Mammal? And is the central left piece an crocodile scute? Second and third photo : Is it true, this could be an Ankylosaur scute? thank you very much!

Hi guys I recently got sent a package from some friends for my birthday which included some nice little goodies including tickets to see the Dinosaurs of china event in Nottingham this summer, Included was this lovely piece identified as purely teeth and bone from a Hadrosaur which was found in the Lance Formation, I was just trying to get any information regarding a species level is possible? I'm not entirely sure if this is possible but hopefully you guys familiar with the lance formation fauna may help. Many thanks, Chris.H

I noticed a number of online suppliers offering Troodon teeth that actually belong to the genus Pectinodon. Thought it would be a good discussion item for a focused post since they can get confusing with the various morphologies of Pectinodon teeth. I'll use publications to illustrate my points and reflect all Campanian & Maastrichtian age teeth of North America. (Edit) A new paper published late in 2017 has turned this taxon upside down. I will try to reflect those changes here but it should not change alter how they are identified against Pectinodon teeth. Specimens from Dinosaur Park Formation previously assigned to Troodon formosus have been reassigned to a new taxon Latenivenatrix mcmasterae and others to a resurrected Stenonychosaurus inequalis. Troodon formosus is now considered invalid. At the very end of this page I will show my understanding of ID's by Formation. Canadian Journal of Earth Sciences, 2017, Vol. 54, No. 9 : pp. 919-935 Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America Aaron J. van der Reest, Philip J. Currie https://doi.org/10.1139/cjes-2017-0031 (Edit 2) Troodon formosus is still considered valid, comments from publication: "Given that the latter had already been synonymized into the senior T. formosus and remained unused for 30 years, Troodon formosus remains the proper name for this taxon, exclusive of L. mcmasterae, and we continue to use it here.: https://www.nature.com/articles/s41598-018-30085-6 Troodontids - Standard morphology These teeth are recurved, laterally compressed and oval in cross section. The Denticles are large and pointed upward on the distal (posterior) carina and minute or absent on the mesial (anterior) carina. Premaxillary teeth have strong denticles on both edges (Figure 8.3 E) Denticles per mm is typically around 4 Maximum length about 9.8mm Figure Examples : Troodontids: Large Morphology The tooth is large about 50% greater and others and can reach 14mm long, recurved and round in cross section. (See figure below 8.3 # 20-21) These have been collected from the North Slope of Alaska. Their is nothing unique to these teeth to describe a new taxon. I've have seen one of these jumbo teeth come from Alberta. Troodon Alaska.pdf Pectinodon bakkeri : Comparison - Troodon and Pectinodon Pectinodon - left image #5 mesial denticles usually absent #11 posterior denticles very large and often rounded much smaller average length of 2.6mm Troodonitid right image #12 posterior denticles point to the tip #13 anterior denticles exist, can be large or absent much larger average length 4 mm but can reach 9.8 Scale bar 1mm Pectinodon teeth can be put into four categories: premaxillary, maxillary, anterior & posterior dentary and all look different. In Figure 9.5 A & B are Premaxillary, C & D Maxillary, E & F Anterior Dentary and G & H Posterior Dentary Premaxillary teeth: long and slender, mesial carina strongly convex and distal is straight. Distal Denticles are large, pointed to the tip and become smaller toward the base. Maxillary teeth are compressed and bladelike. They look like small Dromaeosaur teeth. Anterior denticles are irregular in size and very small (5-6 denticles/mm). Posterior denticles are 3 per/mm. Anterior teeth are leaf shaped with no serrations on the mesial carina. Denticles on the distal edge are 1.6/mm. Denticles are irregular in size. Please note scale bar at 5mm References used: 1) Vertebrate Microfossil Assemblages by Sankey and Baszio 2) Dinosaur Systematics by Ken Carpenter and P. Currie North American Troodontids: My best call I"m sure these will be updated with new research and discoveries. Belly River Group (Alberta) : Latenivenatrix mcmasterae and Stenonychosaurus inequalis (one cannot distinguish between isolated teeth of these two species ID: should be Troodontid indet.) Horseshoe Canyon Formation (Alberta) : Albertavenator curriei (multiple species may exist) Kaiparowits Formation (Utah) : Talos sampsoni Judith River Formation (Montana) : Troodon formosus Two Medicine Formation (Montana) : TMF Troodontid Hell Creek & Lance Formation (Montana, Wyoming, South & North Dakota) : cf Troodon formosus All others (Saskatchewan, Alaska, Colorado etc) : cf Troodon formosus Multiple Troodontids might exist in these other fauna similar to the Belly Group. Since skeletal remains are super rare we may never know if this is true. Identification to a family level "Troodontid indet." may be more appropriate but you can decide that.

A member of the forum asked if I cam put a topic together to help identify claws from the Hell Creek/Lance formation. Its fraught with difficulty since so little has been published and described from these faunas but will attempt to put something together. All subject to discussion and mistakes. Although the focus there is with the dinosaurs of the Upper Maastrichtian its applicable to most of the other faunas of the Campanian and Lower Maastrichtian ages. Ceratopsian indet. This family of dinosaurs include Triceratops, Torosaurus and other large bodied Ceratopsaian yet to be described. Identifying unguals to a Genus/Species level is impossible and these are best identified as Ceratopsian indet. Ceratopsian unguals are best described as being rugose with many pits/holes on the front perimeter of the ungual. There is also a ledge (more pronounced on some than others) on the ventral side as shown by my red marks. I find it difficult to tell the difference between hand and foot unguals of the same size other than the wings are not has pronounced. The more symmetrical the wings are the closer the ungual is to the midline Digit III. Photos are the best way to show what they look like and here are some from my collection Dorsal view Ungual 1 Ventral View Ungual 1 Dorsal View Ungual 2 Ventral View Ungual 2 Dorsal View Ungual 3 Ventral View Ungual 3 An illustration of a Hand (Manus) A photo of a composite foot Leptoceratops indet. A small Ceratopsian in these faunas is a Leptoceratops. Teeth are the most common material found or sold but there are skeletal elements found. Here is an ungual I found in the Hell Creek. The dorsal view is like an isosceles triangle and very compressed. Dorsal View Ventral View Since these are extremely rare here is an additional photo of a associated set of unguals from the Two Medicine Formation An illustration of an campanian foot An illustration of a digit.

Updated March 29, 2023 Changed information on Avisaurus archibaldi A few years ago most of the smaller theropod teeth from the Hell Creek/Lance Formations were identified based on teeth from the Campanian assemblages of North America. Over the past couple of years new discoveries have shed new light on the theropods of the end of the cretaceous and new species have been described. I have addressed these on separate topics but decided to put all of these together to get a better view of the current picture of the upper Hell Creek and Lance formations. If you see any omissions or errors feel free to let me know. Tyrannosaurids: Under Topic: Identification Tyrannosaurid Teeth From North America - General Fossil Discussion - The Fossil Forum Dromaeosaurids: There are two described in the Hell Creek Acheroraptor temertyorum and Dakotaraptor steini however there is mounting evidence that an additional one, mid-size, is present. Saurornitholestes and Dromaeosaurus species are not present. Acheroraptor temertyorum Identification: Like all Dromaeosaurid teeth the denticles are key and different between those on the anterior and posterior carinae. You should easily be able to see that the posterior ones are much larger. If the denticles are identical its probably a juvenile Nanotyrannus tooth. Secondly there are apicobasal ridges on the crown which are diagnostic to this species. There can be several on either side and fewer on posterior located teeth. The teeth are recurved and typically under 1/2" (13mm) long. Dakotaraptor steini Identification: Zapsalis sp. (UPDATE) Identification: Similar to Z. abradens from the Judith River Formation. Very compresses tooth with rounded serrations on the distal side and a smooth mesial edge. One flat tooth surface with longitudinal ridges This form of tooth has been identified as a premaxillary tooth on Saurornitholestes in Alberta. So these teeth should most likely be assigned to Archoraptor but will need new discoveries to confirm it. Update: The unserrated form of this tooth (paronychodon morph) may also be a premaxillary tooth of a Dromaeosaurid or Troodontid. New discoveries are needed to properly assign it. Troodontids: There are at least two present cf Troodon formosus and Pectinodon bakkeri. but only one described Pectinodon bakkeri. cf T. formosus is an easily recognizable tooth. Denticles strongly hooked and turned toward the tip Pectinodon bakkeri significantly smaller 6mm or less than Troodon teeth. Comb like denticles on posterior carina, lacking on the anterior side.. Positionally these teeth have different morphologies can been see in the photo. Reference from : Vertebrate Microfossil Assemblages by Sankey and Baszio Other Teeth: cf Paronychodon lacustris type teeth have several morph types are flat on one side and usually bear three or more longitudinal ridges. Another morp type can be seen in the image. The other side is convex and can be smooth or longitudinal ridges can be present as well.. This is a tooth taxon so placement is questioned by many. May be a Theropod or Pterosaur cf Richardoestesia gilmorei. These teeth may have two different morphologies and can include a long form whose serration density is very high. The information provided is the standard morphology. What is shown comes from the Larsen/Currie's paper. Data they used is from Longrich 2008. Taxonomic placement of these teeth is uncertain. Study included 33 teeth from the Lance & Hell Creek Formation - not all data was collected on these teeth CH Avg: 5.9 mm (Range 3.6 to 10) CBL Avg (14 teeth) 3.8 (Range 2.1 to 4.0) CBW Avg (14 teeth) 1.5 (Range 1.1 to 1.8) CBR: Avg (14 teeth) 0.40 CHR: Avg (33 teeth) 1.60 Density (16 Teeth) Distal: 6.75 (5/mm) or 1.4 mm. Mesial: 9.4 (5/mm) or 1.88 mm DSDI : 1.39 Other Characteristics - Rounded small denticles - Slight posterior recurve Photo Scale Bar : 1 mm References: Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time Derek W. Larson, Philip J. Currie 2013 Longrich NR (2008) Small theropod teeth from the Lance Formation of Wyoming, USA. In: Sankey JT, Baszio S, editors. Vertebrate Microfossil Assemblages: Their Role in Paleoecology Richardoestesia isoceles. Typically are very compressed, elongated and form an isosceles triangle. Fine serrations can be present This species along with the Paronychodon is currently under study and will most likely be described to a new taxon which may not be dinosaurian . Albertonykus sp. is known from bones. Its teeth are very small and pointed. Photo of tooth is from the smaller Mongolian species Mononychus olecranus Morph types isolated small theropod teeth are abundant in these assemblages. Morph types exist and determining the taxonomic affinities of these teeth is problematic. So be prepared to identify these teeth as Theropod indet. Note A lot of what I've described here requires a detailed examination of the serrations. The crisper they are on your tooth the better the opportunity you will have to identify them. having some magnification capability helps Bird: Avisaurus archibaldi This tooth is typically sold as A. archibaldi. Unfortunately this morphology of tooth is most likely Crocodilian per a recent publication, see attached topic. A slightly different morphology pointed out in the paper is viewed as most likely Avian

There are two Tyrannosaurs described in the Hell Creek & Lance Formations, Tyrannosaurus rex and Nanotyrannus lancensis. Teeth from these animals are the number one sought after and coveted item by collectors. I don't understand all the hoopla and prices they command since my friends who I collect with know that I'm not a tooth person and prefer bones and claws. However I've been fortunate to find and acquire a few teeth and will post a several of my nicer ones. My two most favorite T-rex teeth are my biggest and smallest: The Baby (one of the rarest teeth around) is 1 1/8" and when I showed it to Bob Bakkar and Pete Larson they flipped and never had seen a Rex tooth so small and confirmed it was one. Collected from Garfield County, MT. My big Trex one is a rooted Premaxillary tooth at 6". One can see the replacement tooth hole at the bottom of the root T-rex teeth are big and my biggest crown, no root still on the matrix is this 4 5/8" monster. If your are interested none of these teeth have any work done to them. Minor crackfill to the root of the 6" tooth. Serrations are in pretty good shape. .

Updated Nov 25, 2022 Collectors, online sellers and some dealers periodically ask me to help them in the identification of tyrannosaur type teeth. So I thought I would put together a guide from Western North America (US/Canada) to help in identification. The following is the current understanding of those Tyrannosaurids described/known with the stratigraphic unit where they are found. If I missed any let me know. Albertosaurus sarcophagus : Horseshoe Canyon Formation cf Albertosaurus indet: Wapiti Formation Gorgosaurus libratus : Dinosaur Park Formation Gorgosaurus sp. or cf Gorgosaurus: Two Medicine Formation, Oldman Formation, Foremost Formation, Daspletosaurus horneri : Two Medicine Formation Daspletosaurus wilsoni: Judith River Formation Daspletosaurus torosus : Oldman Formation Daspletosaurus sp. or cf Daspletosaurus: Dinosaur Park Formation Dynamoterror dynastes: Menefee Formation Tyrannosaurus rex : Hell Creek Formation, Lance Formation, Frenchman Formation, Scollard Formation, Denver Formation, (Trex fossils are also known from: Livingstone Fm, Laramie Fm, McRae Fm, Willow Creek Fm) Tyrannosaurus sp.: Javelina Formation, Ojo Formation Nanotyrannus lancensis : Hell Creek Formation, Lance Formation cf Nanotyrannus : Frenchman Formation, Scollard Formation, Denver Formation Thanatotheristes degrootorum : Foremost Formation Tyrannosaurid indet. (spp): Judith River Formation, Mesaverde Formation (Group), Fruitland Formation, Aguja Formation Teratophoneus curriei: Kaiparowits Formation Lythronax argestes: Wahweap Formation Nanuqsaurus hoglundi: Prince Creek Formation Tooth Identification Aublysodon mirandus Premaxillary teeth, those without serrations. This dinosaur is considered nomen dubium and teeth ascribed to it belong to other Tyrannosaurs. Albertosaurus sarcophagus Probably the easiest to identify since its the only Tyrannosaurid described from the Horseshoe Canyon Formation. The most important item in acquiring one of these teeth is the provenance of where it was found. Alberta is not adequate to identify it. You need a specific locality like Drumheller or Tolman Bridge. BTW this is true for all the Tyrannosaurid's discussed in this topic. A disposition is also needed for all dinosaur teeth removed from Alberta. These teeth can get quite large from collection of SMM Gorgosaurus libratus (cf, sp.) The first step in identification is Provenance: you need to know State/Province along with the County (USA) or Locality (Canada) where the tooth was found. Differentiating isolated teeth between Gorgosaurus and Daspletosaurus is very difficult and in most cases its indeterminate. A paper that came out in 2005 which was authored by Phil Currie et al. studied isolated teeth from this period looking at tooth and serration morphology. Their conclusion was that "it is difficult to quantifiably distinguish these teeth reliably by taxon". Therefore identifying them as Tyrannosaurid indet. is the easiest approach in those faunas that Gorgosaurus may be present? There is a quantitative process described in a new paper that may help which will be discussed later. Please note that lots of collectors would like to use size to differentiate these teeth from Daspletosaurus. However Gorgosaurus teeth can get quite large as seen in this photo of a Maxilla with one tooth which is over 3 inches and located in the back of this jaw. Daspletosaurus horneri, D. wilsoni, D. torosus (cf, sp.) The first step in identification is Provenance: you need to know State/Province along with the County (USA) or Locality (Canada) where the tooth was found. A paper that came out in 2005 which was authored by Phil Currie et al. studied isolated teeth from this period looking at tooth and serration morphology. Their conclusion was that "it is difficult to quantifiably distinguish these teeth reliably by taxon". Therefore identifying them as Tyrannosaurid indet. is the easiest approach in those faunas that Daspletosaurus may be present? However, its reasonable to say that teeth over 4" are PROBABLY from a Daspletosaurus. There is a quantitative process described in a new paper that may help which will be discussed later. *****Since the Judith River and Two Medicine Formations fall within the range of all three of these species its going to be difficult to assign teeth to a specific species unless you know the age of the deposit it. Denver Fowler: "Hill County exposures are more easy to date because there we have the boundary between the upper Oldman Fm and the lower part of the Dinosaur Park Fm. Havre exposures were called Judith River Fm historically, but we should probably use Oldman & Dino Park now." And maybe ditto for those teeth found in the Belly River Group of Alberta. Denver Fowler "I expect that D. wilsoni is stratigraphically equivalent to the lower part of the Dinosaur Park Formation. At the moment this is based on the fact that the Judith in eastern Montana was deposited at the time when the WI seaway was receded at its maximum (in the Campanian)" Denver's response to my question on this subject. "There isn't currently any evidence for stratigraphic (time) overlap between the species. However, the 2Med and Judith River likely represent enough time such that it would be possible to find D. torosus in the Judith and both D. torosus and D. wilsoni in the 2Med." (Posted by Denver Fowler) Tyrannosaurus rex/ Nanotyrannus lancensis (cf, sp.) Whether you agree or disagree that Nanotyrannus is a valid taxon what is very clear to me is that we have two distinct morphologies of tyrannosaurid teeth at the very end,of the cretaceous. I can say that because I have handled over 1000 teeth over the years ranging from 3 mm to 5 inches two morphs are present in all ranges up to around 2 inches. Serration density through sampling I've done with teeth in my collection do not appear by itself to be a differentiator between these two morphologies. Density will change with size becoming less on larger teeth and can be the same with equivalent size teeth with both morphologies. DSDI (Denticle Size Difference Index) is also not a differentiator and through my sampling and Carr (2004) and indicates that DSDIs decrease in progressively larger specimens, that is, there are fewer mesial denticles per given unit length than distal denticles in large specimens and there are as many or more mesial than distal denticles in small specimens. Also, the DSDI among dentary teeth is higher than that in the maxilla, indicating that mesial denticles are smaller in the dentary than in the maxillary dentition. So how do you tell the difference between these two morphologies. Well, if a tooth is larger than 2 1/2" and has bulk its clearly T rex, regardless of what the serrations say. It cannot be anything else. With small teeth since serrations density is not a differentiator the other characteristic of the tooth plays a key role. I've found that maxillary teeth can be the most difficult to differentiate and a few teeth are just indeterminate, at least with me. The best way to distinguish between the two morphology the shape at the base, compression of the crown and tip and if there is a pinch at the base. Shape at the base T rex dentary teeth and the very anterior maxillary teeth are oval at the base while Nano teeth are unique as tyrannosaurids and rectangular. However, T rex maxillary teeth can be rectangular so you will have to determine if there is a pinch at the base a characteristic found on Nanotyrannus teeth Here are examples of the cross sections of couple small Rex teeth under 1 1/2 inch and Adult Nano's Tyrannosaurus rex Dentary teeth are oval Maxillary Teeth are rectangular Nanotyrannus Bases are rectangular and show a pinch on both sides. Profile of the teeth is another characteristic Nanotyrannus teeth are compressed, with a pointed tip T rex teeth are fat, with a rounded tip, often the serrations wrap around from the mesial to distal carina to form a continuous carina Crown Height Ratios In the study I did, since nothing is published, with 30 Nanotyrannus teeth the average was 2.2 For Trex teeth the mean for Maxillary teeth is 1.75 and for Dentary its around 2 but all these can change depending on position Heterodonty in Tyrannosaurus rex: implications for the taxonomic and systematic utility of theropod dentitions Joshua B. Smith (2005) T rex Premaxillary Teeth can easily be confused with dentary D1 position. Here is a photo of how to determine what you have. Identifying Gorgosaurus and Daspeletosaurus Teeth using Dental Features A recent paper by Hendrickx et al. (Oct 2019) has provided us a way to try to identify certain teeth using dental features. Positional Daspletosaurus & Gorgosaurus teeth have distinct denticle features that can hopefully can be used to differentiate the species which currently does not exist. Together with @Omnomosaurus we are looking at studying this technique to determine if its a practical method for collectors to use for identification, obtain data on campanian tyrannosaurid teeth and try to understand if the results we are getting is any good? We will be using teeth from my collection and members for the study. @dinosaur man has a topic where a lot of member data will be collected. Step 1 The most critical part in using this process is knowing where the tooth sits in the jaw - Premaxillary, Mesial or Lateral Here is a photo of to help in determining its location Paper https://www.researchgate.net/publication/261630184_Morphometry_of_the_teeth_of_western_North_American_tyrannosaurids_and_its_applicability_to_quantitative_classification Step 2 DSDI (Denticle Size Difference Index) needs to be determined DSDI = MC / DC MC = Number of denticles per 5 mm on the mesial carina at mid-carina DC = Number of denticles per 5 mm on the distal carina at mid-crown Mesial Carina is on the outer curvature Distal Carina is on the inside curvature Step 3 1) If your tooth is from a lateral position in the jaw and your DSDI is <0.8 your tooth may be considered a Gorgosaurus or cf Gorgosaurus depending on the locality of where it was found. 2) If your tooth is from a Mesial position in the jaw and your DSDI is >1.2 your tooth may be considered a Daspletosaurus sp. or cf Daspletosaurus depending on the locality of where it was found. Premaxillary Teeth 1) In my opinion all these teeth should be identified as "Tyrannosaurid indet" 2) The paper does make the following statement "In the young specimens of Daspletosaurus, the carinae of the premaxillary teeth are unserrated (TMP 1994.143.1; Currie, 2003) and show the beaded condition. My concern is that it does not specify what size young teeth are and its looking at TMP 1994.143.1 which is a Daspletosaurus sp in Dinosaur Park Fm. Do all Daspletosaurus premax teeth in other faunas have contain similar features? Gorgosaurus premax teeth are not mentioned. Study Currently 33 teeth from the collection of Troodon, Omnomosaurus, dinosaur man Localities included : Judith River Formation (18 teeth), Two Medicine Formation (13 Teeth), Dinosaur Park Formation (1 Tooth), One unknown Results: 1) None of the lateral teeth have had DSDI < 0.8 and could be described as Gorgosaurus 2) Three of the Mesial teeth had DSDI > 1.2 and could be described as Daspletosaurus 3) One of the Premaxillary teeth was not serrated but could not verify if it was a young tooth 4) So 9% of the population can be tentatively assigned Hendrickx et al paper https://palaeo-electronica.org/content/2019/2806-dental-features-in-theropods

Albertonykus borealis was theropod described by Philip Currie and Nicholas Longrich in 2008 from the lower Maastrichtian of the Horseshoe Canyon Formation in Alberta. Its range also extends into Montana, SD and Wyoming in the Hell Creek and Lance Formation. It is noted for having a single hand claw and is a very small theropod, see photo. Very few folks pay attention to small dinosaurs but this one is very cool and material does come out all of the time so I thought it might be interesting to post. If you collect North American dinosaurs the claws are a must have. Teeth have been found on its Asian cousin Mononykus olecranus but no cranial elements to my knowledge have been found in North America. Maybe one of our forum members can find one or has more information to add. Material found in the Hell Creek and Lance formation should be labeled as Trierarchuncus prairiensis I've seen hand and foot claws as well as phalanges sold but few sellers know what they have and label them theropod. I've personally collected some specimens and have purchased others. Published literature and the New York Museum of Natural History Mononykus display help pull the picture together for identification of specimens. Trierarchuncus prairiensis Was described has the Alvarezsaurid from the Hell Creek Formation July 10, 2020 https://www.sciencedirect.com/science/article/pii/S0195667120302469 Hand Claw : They are typically recurved but can be straight. A shallow vascular groove on either side, ventral foramens are present, see second photo (arrow) Carpal : Called the Alular digit and just has one. Photos L to R Medial, Ventral and Dorsal Views Associated Alular Digit : Foot digits in the following post. My collection: