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Hello, I have an old collection from a friend. The theropod dinosaur teeth from Morrison fm, Emery County, Utah. I was wondering where it will be distributed? (Marsh？Allo? or something else) Any insight on this would be greatly appreciated CH:1.5cm CBL:0.6cm MC:5/mm DC:5/mm mesial carina seems to end at bottom ~2/4 of the tooth Thank you for help

I’m wondering if these two teeth (both are from the Morrison Formation in Moffat County, Colorado) have been identified correctly as Allosaurus and Marshosaurus. Here are the measurements of both: Allosaurus: 4cm long serration count is 10/5mm on anterior and posterior carinae base length is 21mm and base width is 13.5 mm (note from dealer: Please note that the base of this tooth is broken and the transition of enamel to root is not present. The base measurement may have been larger.) Marshosaurus: 4cm long serration count is 18/5mm on anterior and posterior carinae base length is 15 mm and base width is 8mm (note from dealer: Please note that the base of this tooth is very near the enamel to root transition a represents a fairly complete tooth.) The serrations on the anterior keel of the tooth extend two-thirds of the distance from tip to base. Images seem to be weirdly mismatched, but I think it’s pretty easy to tell which pictures match with which.

I bought this tooth and the seller named this 'Allosaurus', but the serrations are more dense and the mesial carina stops far before the root. Is this a megalosaurid or allosaurid? Anyone can help? The base width/base length = 4.2mm/12.3mm Locality: Morrison formation, Wyoming Distal carina Mesial carina

I recently purchased a Theropoda indet. tooth from the Lourinhã Formation of Lourinhã, Portugal. I wasn't expecting much initially since it looked like an incomplete tooth and the seller tends to go the safe route with their IDs if it's too vague. But, the serration count was similar to that of the Marshosaurus-like megalosaurid teeth based on @Troodon's guide on the dinosaurs of Portugal. Maybe it's just wishful thinking, but I wanted to see if anyone else had some input before I slap that good old theropoda indet. label on the display. The distal serrations is split down the middle. Mesial serrations were kind of hard to count, but they are at least 20/5mm, the distal serrations are 16/5mm. Not sure if the split serrations are messing with the count, but it should be around that 16/5mm after counting it multiple times with various pictures. I don't know how much further the tooth would have gone had it been complete, but I think the mesial serrations do appear to end before reaching the base. Although I don't know if those serration densities still overlap with other theropods like Allosaurus. Split distal serrations and shape of the base which could be slightly off due to the split serration. Distal serrations. Mesial serrations. Mesial serrations ending? Close up on denticle shape on distal side.

Hey everyone, How do you tell the difference between the teeth of theropods from the Morrison formation, such as Allosaurus, Torvosaurus, Marshosaurus, and/or Ceratosaurus? Any information is appreciated! Thanks!

Hello there. I recently received a small theropod tooth from the Morrison Formation, without any ID. Part of the tip is missing/worn out. At its longest dimension, the tooth measures 1,1 cm. The serration count (Both mesial and dermal) are 6-7 serrations per mm, and about 18-19 per 3 mm. Anyone who's got a good guess, feel welcome to drop a comment here, cause I have no clue if this is a baby Allosaurus, or a small Marshosaurus, Ornitholestes, Coelurus or something completely different.

Hey everyone, I purchased this fossil that was labeled as a Marshosaurus bicentesimus jaw from the Morrison formation in Wyoming. I wanted to get other opinions on it? Is there enough here to say it's a Marshosaurus jaw? Thanks everyone.

Marshosaurus bicentesimus is a midsize theropod in the Morrison Formation in the Megalosauridae family. Over the past few years, teeth are becoming available in the open market simply because dealers/diggers are now more aware of this species and like to sell them. Isolated teeth from the Morrison Formation are very difficult to diagnose because of their similarity and all require an understanding of additional characteristics than normal, in hopes of properly identifying them. The best I can do is to look at other reference publications some which include similar teeth from Portugal and Germany which describe morph types and then assign them to the best taxon. I also have been able to obtain information from C. Hendrickx recent publication Taxonomic identification of isolated theropod teeth 2019 that took measurements of these teeth and this edit reflects that information. . The following information is needed to identify these teeth: 1)Photo of tooth, both sides and base and one of the mesial edge (outer) 2)Serration density of both edges 5 mm wide at midline 3)Dimensions: CBL, CBW, CH 4) Locality: State and County Three Key Characteristics :. 1) Mesial Carina should extend down at least 2/3 First and most important since this is a Megalosaurid the anterior carina (serrations) only come up to 2/3 of the way down the keel. 2) Serrations on both edges should be different (Hendrickx Study 8 teeth) The serrations are finer than most other large theropods in the Morrison. Mesial edge must be finer than Distal DSDI : Denticle size density index = Mesial Density ÷ Distal Density Should be Greater than 1.15 Mesial at Centerline MC : around 20/ 5 mm Distal at Centerline DC : 15-17/ 5mm, posterior teeth may be higher 3) Crown Base and Height ratios These teeth are compressed and the ratio looks at that compression. Marshosaurus teeth must fall into these parameters CBR: Crown Base Width (CBW) ÷ Crown Base Length (CBL) = Dentary (around 0.5-0.6), Maxillary (around 0.3) CHR: Crown Height Ratio (CH) ÷ Crown Base Length (CBL) = 1.5 to 2.5 may be lower on distal teeth 4) Other Characteristics Might show light transverse undulations Might show some short Interdental sulci but typically absent Representation of teeth that are similar to Marshosaurus C1-3 Reconstruction Skull of Marshosaurus from Utah Museum of Natural History. So you can see variation of the teeth in jaw Reference: 1) Hendrickx, C., Mateus, O., and Araújo, R. 2015. The dentition of megalosaurid theropods. Acta Palaeontologica Polonica 60 (3): 627–642. 2) Journal of Iberian Geology June 2017, Volume 43, Issue 2 , pp 257-291 Analysis of diversity, stratigraphic and geographical distribution of isolated theropod teeth from the Upper Jurassic of the Lusitanian Basin, Portugal 3) Multivariate and Cladistic Analyses of Isolated Teeth Reveal Sympatry of Theropod Dinosaurs in the Late Jurassic of Northern Germany Oliver Gerke, Oliver Wings Published: July 6, 2016 https://doi.org/10.1371/journal.pone.0158334 4) A second new Theropod dinosaur from the late Jurassic of east central Utah 1979 by J Madsen

Recently acquired this very nice tooth from Morrison fm, Moffat County, Colorado. I think it is Marshosaurus, am I right? I am afraid to clean it right now because the tooth is very fragile. Total length is ~1.6 cm. Ruler is in inches, so 1 line=1/16 inch=~1.5 mm, so distal serration density looks to be around 4/mm; mesial carina seems to end at bottom ~3/4 of the tooth, as I understand, these are Megalosaurid characteristics. Although I couldn't find any info on other medium-small sized theropods, like Tanycolagreus, Coelurus or Ornitholestes. Thank you for help! @Troodon By the way, took those pictures with AmScope USB microscope, very useful tool for detailed teeth

I saw this Marshosaurus tooth for sale so decided to check it out since some of you might be interested in it. I have some concerns why I decided to post it. If interested you need to do some work. Its not easy to TRY to ID a tooth and most are just identified to a morphology so no guarantee any of this will get answers. 1) The mesial carina is hard to see but seems to extend close to the base. In Megalosaurids it should only extend + 1/2 of the crown height. If interested you should request sharper photos to get a better look. 2) The denticles seem to be apically directed. In Megalosaurids they should be positioned perpendicular to the carina. Again if interested request additional close-up photos. 3) To do your homework properly request a serration count 5mm wide in the center of the distal serrations. With the mesial serrations missing its a data point you are missing. You should be around 16 or above for the distal side 4) The very tip looks it might a resto. They mention that the tooth has had minor crack filling yet there is visible crack in the top photo. Find out were the fill was done and if anything was done to the tip or was that the fill. A closeup of the tip should be requested. 5) The CRB, Crown Base ratio, should be around .5 to confirm that fits within what is seen on marshosaurus. So you need to request the length and width at the base, see photo to insure its done properly Must use the dimensions of a complete tooth.