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From the album: Hell Creek / Lance Formations
Interesting blue color near the base, and some feeding wear at the tip of this immature Tyrannosaurid tooth.-
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Curious about iron and pyrite in the Hell Creek Formation
Maniraptora posted a topic in Questions & Answers
Hey all! When I went on a collecting trip in the Hell Creek Formation in Montana, there were many iron concretions, and I've noticed that some specimens from there appear to be iron-stained. This makes me wonder if pyrite could be among the minerals involved in fossil preservation there. Are some of the bones found in the Hell Creek pyritized, and how could those be distinguished from others preserved differently? If so, do those Hell Creek specimens ever develop "pyrite disease," and what would be the warning signs to look out for? Thanks so much for sharing your knowledge! -
Identification Troodontid teeth may be identified by their exaggerated, triangular, apically directed posterior denticles1. Pectinodon bakkeri is the only Troodontid species currently named from Lancian strata; its teeth are on average smaller and more gracile than those of its cousin, Troodon. Comments Pectinodon (meaning "comb-tooth")1 is a tooth taxon, since no remains attributable to the genus beyond teeth have been found. Pectinodon seems to be a rare member of the Hell Creek fauna, with their teeth being fairly uncommon. It was a small theropod, with teeth that couldn't handle stresses as well as their Dromaeosaurid and Tyrannosaurid relatives2. This coupled with their small size suggest that Pectinodon was a small/soft prey specialist, preferring the rodent-sized mammals of the time, lizards, insects, etc. Some researchers have proposed omnivory as a possibility for Troodontids (cf. Holtz et al. (1998))3. References 1. Carpenter, Kenneth. "Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of en new species of theropod." Contributions to Geology 20.2 (1982): 123-134. 2. Torices A, Wilkinson R, Arbour VM, Ruiz-Omeñaca JI, Currie PJ. "Puncture-and-Pull Biomechanics in the Teeth of Predatory Coelurosaurian Dinosaurs." Curr Biol. 2018 May 7;28(9):1467-1474.e2. 3. Holtz TR Jr, Brinkman DL, Chandler CL. "Denticle morphometrics and a possible omnivorous feeding habit for the theropod dinosaur Troodon." Gaia. 1998; 15: 159–166.
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Hello everyone, I recently finished preparing some ribs that I posted in the fossil preparation category and am having some trouble IDing them. One is fairly complete and the other 2 are fragments. They were found grouped together in Garfield County, Montana on a ranch. I think they resemble some Thescelosaurus ribs that I've seen in some papers but not enough to be confident in assigning an ID. Here are front and back views of each rib individually. I also found numerous bits of other bones in the jacket one of them being what I think is a carpal of something but haven't had time to do much digging. Here are some top and bottom views. I know you've said ribs are tricky to ID @Troodon but if you have any insight it would be very appreciated. Thank you all for your time and help.
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"That some of these teeth are mammalian incisors there can be but little doubt..." - O. C. Marsh1 This kind of incisor-like ("incisiform") tooth was originally thought to have belonged to a large, Cretaceous mammal. Later discoveries revealed that these teeth were actually the front teeth ("premaxillary teeth") of Tyrannosaurs - and are now known as a hallmark of their clade, Tyrannosauroidea (along with fused nasals). Closely-spaced, parallel grooves on bones suggest that Tyrannosaurs used these teeth to selectively scrape meat from bone2. Identification Tyrannosaurid premaxillary teeth have a "D"-shaped cross section, with the lingual face flattened, and often have an apicobasal ridge on the midline of the lingual face. In more technical language, "...premaxillary teeth bear lingually rotated mesial and distal carinae forming a salinon cross-section at mid-crown height, and a highly convex labial aspect as in tyrannosauroids generally. In mesial/distal views carinae are sinuous, transitioning from lingually convex near the base to lingually concave approaching the occlusal surface. Carinae terminate prior to reaching the root/crown juncture. Mesial and distal aspects of the crown are depressed, yielding a weakly hourglass-shaped cross-section at the crown base... The carinae lack serrations [likely ontogenetically variable]... As in other tyrannosauroids, teeth exhibit a pronounced lingual ridge"3. Most of the current literature supports only one Tyrannosaurid species in the Hell Creek formation, Tyrannosaurus rex, a hypothesis subject to change in light of new evidence. Comments This tooth has no discernible antemortem wear. The collector appears to have applied some preservative coating, giving the enamel a slightly sharper gloss. Given the size, this is from a very young animal (smaller than "Jane", BMRP 2002.4.1). References 1. Marsh, O.C., 1892, "Notes on Mesozoic vertebrate fossils", American Journal of Science, 44: 170-176 2. David W.E. Hone and Mahito Watabe, "New information on scavenging and selective feeding behaviour of tyrannosaurs", Acta Palaeontologica Polonica 55 (4), 2010: 627-634 doi: http://dx.doi.org/10.4202/app.2009.0133 3. Zanno, L., Tucker, R.T., Canoville, A. et al. Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record. Commun Biol 2, 64 (2019). https://doi.org/10.1038/s42003-019-0308-7
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"That some of these teeth are mammalian incisors there can be but little doubt..." - O. C. Marsh1 This kind of incisor-like ("incisiform") tooth was originally thought to have belonged to a large, Cretaceous mammal. Later discoveries revealed that these teeth were actually the front teeth ("premaxillary teeth") of Tyrannosaurs - and are now known as a hallmark of their clade, Tyrannosauroidea (along with fused nasals). Closely-spaced, parallel grooves on bones suggest that Tyrannosaurs used these teeth to selectively scrape meat from bone2. Identification Tyrannosaurid premaxillary teeth have a "D"-shaped cross section, with the lingual face flattened, and often have an apicobasal ridge on the midline of the lingual face. In more technical language, "...premaxillary teeth bear lingually rotated mesial and distal carinae forming a salinon cross-section at mid-crown height, and a highly convex labial aspect as in tyrannosauroids generally. In mesial/distal views carinae are sinuous, transitioning from lingually convex near the base to lingually concave approaching the occlusal surface. Carinae terminate prior to reaching the root/crown juncture. Mesial and distal aspects of the crown are depressed, yielding a weakly hourglass-shaped cross-section at the crown base... The carinae lack serrations [likely ontogenetically variable]... As in other tyrannosauroids, teeth exhibit a pronounced lingual ridge"3. Most of the current literature supports only one Tyrannosaurid species in the Hell Creek formation, Tyrannosaurus rex, a hypothesis subject to change in light of new evidence. Comments This tooth exhibits some antemortem wear at the apex (pictured), on the carinae, and near the base of the lingual apicobasal ridge. Given the size, this is from a juvenile animal (smaller than "Jane", BMRP 2002.4.1). References 1. Marsh, O.C., 1892, "Notes on Mesozoic vertebrate fossils", American Journal of Science, 44: 170-176 2. David W.E. Hone and Mahito Watabe, "New information on scavenging and selective feeding behaviour of tyrannosaurs", Acta Palaeontologica Polonica 55 (4), 2010: 627-634 doi: http://dx.doi.org/10.4202/app.2009.0133 3. Zanno, L., Tucker, R.T., Canoville, A. et al. Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record. Commun Biol 2, 64 (2019). https://doi.org/10.1038/s42003-019-0308-7
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From the album: Hell Creek / Lance Formations
One of my favorites as a kid - the archetypical Ankylosaurian - Ankylosaurus. Ankylosaurus teeth appear to be fairly uncommon in Hell Creek - some paleontologists have suggested that Ankylosaurus may have lived in the highlands or nearer the coast of Laramidia. Most "Ankylosaurus" teeth you see for sale are actually Nodosaurid (cf. Denversaurus), for whatever reason, they seem to be far more common. Ankylosaurus teeth also often have wear facets, as this one does. The denticles give their teeth a "leaf-like" appearance. Given their shorter stature, Ankylosaurians probably were low-browsers. This one was found by a rancher last year, and was rediscovered and prepped out of the matrix in October.- 1 comment
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From the album: Hell Creek / Lance Formations
This kind of incisor-like ("incisorform") tooth was originally thought to have belonged to a large, Cretaceous mammal. Later discoveries revealed that these teeth were actually the front teeth ("premaxillary teeth") of Tyrannosaurs - and are now known as a hallmark of their clade, Tyrannosauroidea. Closely-spaced, parallel grooves on bones suggest that Tyrannosaurs used these teeth to scrape meat from bone. Given the size, this is from a very young animal. Should Nanotyrannus be valid, then this should be considered an indeterminate Tyrannosaurid. -
From the album: Hell Creek / Lance Formations
This kind of incisor-like ("incisorform") tooth was originally thought to have belonged to a large, Cretaceous mammal. Later discoveries revealed that these teeth were actually the front teeth ("premaxillary teeth") of Tyrannosaurs - and are now known as a hallmark of their clade, Tyrannosauroidea. Closely-spaced, parallel grooves on bones suggest that Tyrannosaurs used these teeth to scrape meat from bone. Given the size, this is from a juvenile animal (smaller than "Jane"). Should Nanotyrannus be valid, then this should be considered an indeterminate Tyrannosaurid.-
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From the album: Hell Creek / Lance Formations
Pectinodon (meaning "comb-tooth") is a tooth taxon, since no remains attributable to the genus beyond teeth have been found. Pectinodon seems to be a rare member of the Hell Creek fauna, with their teeth being fairly uncommon (though being so small, I'd guess that few people actively search for them). It was a small Troodontid theropod, with teeth that couldn't handle stresses as well as their Dromaeosaurid and Tyrannosaurid cousins (Torices et al. (2018)). This coupled with their small size suggest that Pectinodon was a small/soft prey specialist, preferring the rodent-sized mammals of the time, lizards, insects, etc. Some researchers have proposed omnivory as a possibility for Troodontids (cf. Holtz et al. (1998)). Troodontids famously are regarded as among the most intelligent dinosaurs for their large brain size / body size ratio. This notion serves as fodder for speculation that had the dinosaurs not gone extinct, Troodontids (Pectinodon being (one of?) the last) would have continued to grow in intelligence and develop sentience and civilizations. Troodontid teeth like Pectinodon can be easily identified by their small size, exaggerated, triangular, apically oriented posterior serrations.-
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From the album: Dinosaurs
These strange, incisor-like teeth were originally thought to have belonged to a large Cretaceous mammal. Later discoveries showed that these teeth matched the front teeth of young Tyrannosaurs quite well. Given closely spaced, parallel feeding traces on bones, these "incisorform" teeth likely were used to scrape meat from bone. -
From the album: Dinosaurs
A rare tooth from the Hell Creek formation. Curiously most Ankylosaurian teeth you see online are actually Nodosaurid. This one is the Ankylosaurus. -
From the album: Dinosaurs
Plant roots often intrude upon a fossil's resting place, leaving behind white streaks when removed. -
I'll break my trip report to South Dakota into two parts. First will be my visit to the BHI followed by collecting adventure The purpose of going to the BHI was to pick up the Leptoceratops maxilla's I left during my June trip. Pete has been collecting and pulling together specimens to understand and possibly describe this ceratopsid in the Hell Creek. The material he's collected so far appears to be from an adult and is much smaller than L. gracilis. My maxilla's seem to fit the smaller morphotype. In addition, the BHI provided me two sets of replicas of my specimens, pretty cool. Tankankaceratops is a controversial ceratopsian described by Ott and Larsen 2010. It's a small Triceratopsini known from a partial skull. Pete showed me its occipital condyle which is fused and indicative of an adult. Very cool nasal horn core. Here is a close up of Struthiomimus sedens hand/part of arm... the business end. Good reference photos A new addition to the museum is a cast of a juvenile Tarbosaurus skeleton that was being assembled in June trip Here is some White River material that was recently collected. Think Pete said the top left skull was a rare Camelidae Hespercyon Took photos for reference of the metatarsals from Nanotyrannus Another reference bone a Nanotyrannus carpal bone, much longer than any found on T rex.
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From the album: Hell Creek / Lance Formations
It's remarkable that the minute features of this tooth can be preserved with such clarity after 66 million years! -
From the album: Hell Creek / Lance Formations
The preservation of theropod teeth doesn't get much better than this. -
From the album: Hell Creek / Lance Formations
The denticles and enamel of this Ankylosaurus tooth are exceedingly well-preserved.-
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Can radioactive fossils damage other specimens?
Maniraptora posted a topic in General Fossil Discussion
I know next to nothing about radioactivity-- enough to know licking fossils is inadvisable, although I'll admit that wasn't terribly disappointing news. What I'm wondering is whether specimens not radioactive enough to endanger a person are capable of damaging other specimens. Is there a need to segregate displays here, or am I just confused about the mechanics of this? My specific reason for asking is that at the moment I'm planning for my current favorite mineral specimen (which I am babying forever), an almandine garnet from Broken Hill, New South Wales, Australia, to share a small shelf area with a tooth from the phosphate deposits in Oulad Abdoun Basin, Morocco and a few dinosaur bone pieces from the Hell Creek Formation of Montana (one from Dawson County) and Lance Creek Formation of Niobrara County, Wyoming. The shelf is not enclosed, by the way. Thanks for your help! -
Late Cretaceous sturgeons from K/Pg impact deposits in North Dakota
Oxytropidoceras posted a topic in Fossil News
'Hell fish' likely killed by dinosaur-ending asteroid is preserved in stunning detail Joanna Thompson, Live Science, October 12, 2022 Four exceptional fossils represent newly described species. https://www.livescience.com/3d-sturgeon-fossils-tanis The open access paper is: Hilton, E.J. and Grande, L., 2022. Late Cretaceous sturgeons (Acipenseridae) from North America, with two new species from the Tanis site in the Hell Creek Formation of North Dakota. Journal of Paleontology, pp.1-29. Another open access paper is: DePalma, R.A., Smit, J., Burnham, D.A., Kuiper, K., Manning, P.L., Oleinik, A., Larson, P., Maurrasse, F.J., Vellekoop, J., Richards, M.A. and Gurche, L., 2019. A seismically induced onshore surge deposit at the KPg boundary, North Dakota. Proceedings of the National Academy of Sciences, 116(17), pp.8190-8199. Yours, Paul H.- 1 reply
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From the album: Hell Creek / Lance Formations
Pectinodon (meaning "comb-tooth") is a tooth taxon, since no remains attributable to the genus beyond teeth have been found. Pectinodon seems to be a rare member of the Hell Creek fauna, with their teeth being fairly uncommon (though being so small, I'd guess that few people actively search for them). It was a small Troodontid theropod, with teeth that couldn't handle stresses as well as their Dromaeosaurid and Tyrannosaurid cousins (Torices et al. (2018)). This coupled with their small size suggest that Pectinodon was a small/soft prey specialist, preferring the rodent-sized mammals of the time, lizards, insects, etc. Some researchers have proposed omnivory as a possibility for Troodontids (cf. Holtz et al. (1998)). Troodontids famously are regarded as among the most intelligent dinosaurs for their large brain size / body size ratio. This notion serves as fodder for speculation that had the dinosaurs not gone extinct, Troodontids (Pectinodon being (one of?) the last) would have continued to grow in intelligence and develop sentience and civilizations. Troodontid teeth like Pectinodon can be easily identified by their small size, exaggerated, triangular, apically oriented posterior serrations.-
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This is part two of my fall trip the first part was posted under trips to the museum Link Part one: Sept Dig Trip: Black Hills Institute - A Trip to the Museum - The Fossil Forum A short trip but like many enjoyed it, found some nice items and the weather was much better that what I saw in June. First let me share some photos of items collected in June that are finished. All Edmontosaurus annectens, Hell Creek Formation Skull element : quadrate 13.75" long Before: After to see its location Center Toe Bone Digit III -1, 5" Front to back Before After Chevron : 14.5" Long , second one in two seasons this size Before Getting there is half the fun SD 85 where I am is straight for miles and miles and miles. They could use some rain. Roadside store It's common to run into Cows crossing a pasture and they typically move but Horses that are stubborn and don't want to move, they are in charge Heavy horn works beautiful herd Love the mailboxes
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Hi y'all, recently acquired this beautiful multituberculate. Total tooth height is 3 mm. Mesodma sp. P4? @jpc Cf. Mesodma sp. Hell Creek Fm., Garfield Co., MT, USA 3 mm
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Hi all! Got another tooth here I'm looking for help on ID with. Only unfortunate thing is the exact county is unknown. Bought from an older collection so all the seller knew for sure is Hell Creek Formation. Seller has been very cooperative and is also very interested if an ID can be found with that little caveat. It was labeled dakotaraptor from the old collection. Initial thought was R. gilmorei or nano but doesn't look to have the defined nano pinch. No mesial serrations visible or can be felt. Best picture he could get of the serrations is below as well. Appreciate any input! Thanks!
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From the album: Hell Creek / Lance Formations
As a theropod tooth aficionado, I thought it useful to compare two families present in the Hell Creek Formation. They become increasingly difficult to distinguish as they get smaller, but this graphic presents some features which may be used to differentiate them on two similarly-sized exceptional specimens. Keep in mind there is some variability due to position, ontogeny, etc., so it's beneficial to study more than one tooth for each family.-
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From the album: Hell Creek / Lance Formations
Not the prettiest tooth, but I very much enjoy fossils like this that demonstrate behavior and tell a story. T. rex and other Tyrannosaurs were unusual among theropods in that they consumed the entire carcass of an animal - bones and all. Most theropod dinosaurs have ziphodont teeth, thin and knife-like, good for cutting muscle from bone. The thick and robust teeth of adult Tyrannosaurs, coupled with their incredible bite force, allowed them to shatter and pulverize bone - even those of the large, formidable herbivores they hunted. Despite the robustness of their teeth, Tyrannosaurs often broke them in the process of biting. It may have been a while before the broken tooth was replaced by a new one, so in the meantime, the broken tooth would continue to accumulate wear. This is one such tooth, a large portion of the tooth was broken off when the animal bit into another dinosaur, and it was still used afterwards for some time before it was replaced. Based on the placement and extension of the carinae to the base of the tooth, and the size, this was an anterior tooth (at the front of the mouth, probably the first dentary tooth) of an adult individual. See Schubert & Ungar (2005) for a discussion on Tyrannosaur tooth wear features (open-access).
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