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Is this an astragalus to perhaps an insectivore, squirrel, or other type of rodent? Found in the Nebraska badlands – private ranch – early Oligocene, Brule Formation, Orella Member, about 20 feet above the Upper Purplish White (UPW) ash layer – a Harvester ant mound specimen. The bone (3 to 4 mm in length) has a rounded end which I never seen before on any astragulus. Two specimens photo’ed in this post. Any help in ID’ing this fossil would be greatly appreciated, Thank you.
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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 This is a large anterior dentary tooth, recovered by screening matrix from a channel deposit in central Montana. 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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With the only diatom green formation about 4 hours away, I decided to see what I can find the somewhat lose matrix sandstone of the Pittsberg Bluff Formation. The attached image was taken at 100X and captured in a 5 mpx camera. Processed in PS. I've drawn a pentagram around the object of interest at bottom center of image (also the oblect to the right of it looks interesting - maybe?). Is this just a waste of time, or can one find micro fossils in sandstones? thanks.
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From the album: Hell Creek / Lance Formations
An overlooked member of this ecosystem - the humble frog. The night soundscape may have been dominated by them and insects, as in many forested/swampy ecosystems today. -
Hi all, This jaw was just listed on a particular auction site and caught my eye. Locality according to the seller is Hell Creek formation, Montana. The fossil is 15mm long. Their ID is just "dinosaur" of unknown species. To my amateur eyes, the size and "shelf" on the inside of the bone makes me think lizard, but the teeth really look like those of dromaeosaurs. Any thoughts on ID? Lizard, juvenile dromaeosaur, or bird even?
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From the album: Micros from the Triassic of Aust Cliff, UK
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Trying to get input on this form I found in sediments from the Calvert Formation. This test batch is from a mudstone, broken up and reduced through no. 20 and no.120 testing sieves. The close up is using a 40/0.65 lens
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From the album: Hell Creek / Lance Formations
One species I was hoping to find - a small Orectolobiform shark from the Hell Creek formation. It was named in 2019 for its teeth shaped like the spaceships in "Galaga." Amended from Gates 2019: “Orectolobiform shark possessing the following autapomorphies: central cusp with distinctly swollen lingual face forming a clearly demarcated constriction, or neck, between the cusp and the root; labial surface of central cusp ornamented with a raised ridge or closely arrayed plications, which in most cases are distributed in such a pattern as to follow the slope of the heels; convex heels, well developed both mesial and distal to the central cusp with a distinct convex angle mid-distance along slope seen in anterior teeth and some lateral teeth. This taxon is further differentiated by the following suite of shared characters: anterior teeth possess distinct, high central cusp; heels on lateral teeth slightly serrated; heels of anterior teeth and some lateral teeth do not slope gradually toward root lobes, but are instead squared-off or rounded at their terminus; one or two rounded diminutive cusplets may be present although this trait varies among individual teeth; apron is generally broadly rounded and shows a bifid habit on some but not all specimens; root lobes enlarged on [labial] side of tooth compared to more constricted structure on [lingual] side, bestowing an exaggerated heart-shape in basal view; a central foramen pierces between the root lobes with the foramen divided by thin struts in some teeth.”-
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From the album: Hell Creek / Lance Formations
Richardoestesia teeth have very fine serrations. A couple of mm of the tip was reattached after I found it in the matrix I was scrupulously searching.-
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From the album: Hell Creek / Lance Formations
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From the album: Hell Creek / Lance Formations
A monitor lizard from the very end of the Cretaceous. The carinae are slightly serrated, and in basal view the mesial carina projects from the silhouette like a wing.-
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From the album: Hell Creek / Lance Formations
Among the iridescent mollusk shell shrapnel, lies a molar from a small Cretaceous mammal.-
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From the album: Hell Creek / Lance Formations
A hybodont "shark" found in a channel deposit. This was among the last of the hybodonts - a group that spanned nearly 300 million years before going extinct along with the non-avian dinosaurs 66 million years ago.-
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From the album: Hell Creek / Lance Formations
An Orectolobiform shark that swam the rivers of the Hell Creek ecosystem. Their teeth closely resemble those of the modern carpet shark, the "wobbegong." This was found in matrix from a channel deposit.-
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From the album: Hell Creek / Lance Formations
Triceratops's smaller cousin, this Ceratopsian lacked horns. Note the single root. This is a very small tooth, likely from a baby (the root being present also means that unfortunately this dinosaur did not survive into adulthood).-
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From the album: Hell Creek / Lance Formations
A mammal tooth from the group that includes the marsupials. Found in a channel deposit, it's remarkable that the roots are still intact.-
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- cretaceous mammal
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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: Hell Creek / Lance Formations
A small tooth from a Dromaeosaurid "raptor" dinosaur, located in an anterior position in the mouth. Found in a channel deposit.-
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Trying so hard to find micropaleontology slides. Any suggestions on where to get good quality slides?
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My small collection - not sure how to even begin to identify these. These all came from seiving about 3 gallons of gravel from the Eastern portion of the NSR. Any help on identifying these would be greatly appreciated!
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I have been working on my undergraduate thesis for a little town called Cow Head in Newfoundland, Canada. This area is a part of the Cow Head group, specifically the Stearing Island beds, making it Lower Ordovician. I'm asking about the little circular guy in the top right. If anyone has any idea what it may be (if it even is a fossil) that would be great, any help would be greatly appreciated! I would love to credit you in our paper if you'd like! I attached images of the thin section in both plane polarized and cross polarized light. Thank you!
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I'm hazarding a guess as a P1 element of Idiognathodus?, or is it something else? seems a little wide for a conodont? Pennsylvania stark shale. Yeah or neigh? Thanks! Bone
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I was given this microfossil, which has no provenance whatsoever. Any suggestions would be most helpful.
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Unknown Microfossil from Pennsylvanian aged Excello Shale in thin section
Samurai posted a topic in Fossil ID
Hello! I was making some thin sections of some material from the Excello shale and found a very large and bizarre structure. Sorry in advance it was too big for my microscope camera to really capture it all, but here is the specimen in question its most likely coated in apatite/phosphate? along with small radiolarian/sponge spicules surrounding it I sent a photo to my professor and he said it could be something new but he would have to see it in person (he is an expert in Radiolarian microfossils) I wanted to post it here and see if anyone had any ideas to throw out. Here it is under 4x power (it is still a little bit of a "thick section" rather than thin section but I plan to grind it down at another time) I don't think it is a radiolarian (unless it is a ginormous one) as the largest I have found from the Excello was about 1000 microns Here is the largest one I can confirm is a Radiolarian (Entactinaria sp.?): Bonus Rad that shows possible apatite/phosphate coating in more detail (old photo) Let me know if you guys have any suggestions or questions let me know and Ill try to aid in any way I can.-
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