McInnis Canyons Mygatt-Moore Quarry Gives Up Fossil Clues

John and I have been continuing our research out at the Mygatt-Moore Quarry in western Colorado, and recently had a paper on one of our findings published in the Journal of Vertebrate Paleontology in May.

Foster, John R. and Hunt-Foster, Rebecca K.(2011) 'New occurrences of dinosaur skin of two types (Sauropoda? and Dinosauria indet.) from the Late Jurassic of North America (Mygatt-Moore Quarry, Morrison Formation)', Journal of Vertebrate Paleontology, 31: 3, 717 — 721 DOI: 10.1080/02724634.2011.55741

We work each summer at this quarry under a paleontological permit from the Bureau of Land Management, which is located in the McInnis Canyons National Conservation Area (NCA), near the Colorado/Utah state line. “The national significance of the area's paleontological resources is one of the many reasons this special place was designated as a National Conservation Area,” said Katie Stevens, NCA Manager for the BLM’s Grand Junction Field Office. “With experts like John and ReBecca working in these quarries, we can recover and share this exciting and important scientific information with the public.” John is currently working under a scientific grant from the BLM to better understand the extent of the quarry and the conditions that made it such an ideal location for preserving fossils [details].

The first specimen was located by Jim Kirkland and his expedition to the quarry in 1993 (MWC 1903). A expedition member, Dan Libecap, discovered the second specimen (MWC 5537) in 2003. Two of our museum volunteers, Kay Fredette and Ray Bley, uncovered the most recent specimen (MWC 6718) in 2008.

Two of the three specimens (MWC 6718 & 5537) are possibly from sauropods, and we attributed the third specimen to Dinosauria indeterminate (MWC 1993). The two possible sauropod specimens represent the first occurrence in the Morrison Formation of preserved sauropod skin associated with abundant nearby specimens of Apatosaurus. They also show how similar the general structure of skin patterns within known Morrison diplodocids are.

Specimen MWC 6718 - carbonized sauropod? skin impression from the Mygatt-Moore Quarry. Morrison Formation (Upper Jurassic) of Mesa County, Colorado. scale bar =5 cm

These discoveries were unique because the soft tissue associated with the skin was preserved as carbonaceous layers rather than as trace fossil impressions, yielding better information about skin pattern, scale size and scale shape. This discovery is is the sixth occurrence recovered from the Morrison Formation.

If you would like a PDF of this paper please contact me here or by email and I would be happy to share one with you. We plan for this paper to be the first of many that will be published over the next few years. Below is a complete bibliography of research from Mygatt-Moore Quarry that has been done to date (PDF's of select papers are also available):

Foster, John R. and Hunt-Foster, Rebecca K. (2011). New occurrences of dinosaur skin of two types (Sauropoda? and Dinosauria indet.) from the Late Jurassic of North America (Mygatt-Moore Quarry, Morrison Formation) Journal of Vertebrate Paleontology, 31 (3), 717-721 : 10.1080/02724634.2011.55741

Foster, John R. 2007. Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indian University Press, 416 pages.

Foster, John R; Hunt, ReBecca K; King, Lorin. 2007. Taphonomy of the Mygatt-Moore quarry, a large dinosaur bonebed in the Upper Jurassic Morrison Formation of western Colorado. Geological Society of America, 2007 annual meeting, Abstracts with Programs - Geological Society of America, vol. 39, no. 6, pp.400

King, Lorin R; Foster, John. 2006. Under the feet of giants; an investigation of the small vertebrates at the Mygatt-Moore Quarry, Morrison Formation, western Colorado. Sixty-sixth annual meeting, Society of Vertebrate Paleontology; abstracts of papers. Journal of Vertebrate Paleontology, vol.26, no.3, Suppl., pp.85

King, Lorin R; Foster, John R; Scheetz, Rodney D. 2006. New pterosaur specimens from the Morrison Formation and a summary of the Late Jurassic pterosaur record of the Rocky Mountain region. In (editors - Foster, John R; Lucas, Spencer G) Paleontology and geology of the Upper Jurassic Morrison Formation. Bulletin - New Mexico Museum of Natural History and Science, vol.36, pp.109-113

Foster, John. 2005. Evidence of size-classes and scavenging in the theropod Allosaurus fragilis at the Mygatt-Moore Quarry (Late Jurassic), Rabbit Valley, Colorado. Sixty-fifth annual meeting, Society of Vertebrate Paleontology; abstracts of papers. Journal of Vertebrate Paleontology, vol.25, no.3, Suppl., pp.59

King, Lorin; Foster, John; Scheetz, Rodney. 2005. Mesadactylus and other new pterosaur specimens from the Morrison Formation (Upper Jurassic) of western Colorado. Sixty-fifth annual meeting, Society of Vertebrate Paleontology; abstracts of papers. Journal of Vertebrate Paleontology, vol.25, no.3, Suppl., pp.78

Kirkland, James I. 1998. Morrison fishes. Modern Geology 22: 503-533

Tidwell, W.D., Britt, B.B., and Ash, S.R. 1998, Preliminary floral analysis of the Mygatt-Moore Quarry in the Jurassic Morrison Formation, west-central Colorado: Modern Geology 22: 341-378

Chin, K. and Kirkland, J.I. 1998. Probable herbivore coprolites from the Upper Jurassic Mygatt-Moore Quarry, Western Colorado. Modern Geology 23: 249-275.

Kirkland, J. and K. Carpenter. 1994. North America's first pre-Cretaceous ankylosaur (Dinosauria) from the Upper Jurassic Morrison Formation of Western Colorado. Brigham Young University Geology Studies, 40:25-42.

Kirkland, James I; Armstrong, Harley J. 1992. Taphonomy of the Mygatt-Moore Quarry, middle Brushy Basin Member, Morrison Formation (Upper Jurassic), western Colorado. Society of Vertebrate Paleontology, fifty-second annual meeting. Journal of Vertebrate Paleontology, vol. 12, no. 3, Suppl., pp.37A

Mygatt, Peter. 1991. The Mygatt-Moore Quarry, Rabbit Valley, Mesa County, Colorado. Pages 57-58 in (editor - Averett, Walter R.) Guidebook for dinosaur quarries and tracksite tour, western Colorado and eastern Utah. Grand Junction Geol. Soc., Grand Junction, CO

Fieldwork Friday #12

Yikes! I have not done a Fieldwork Friday in a year! Something is just wrong with that!! I have been pretty busy at work recently. I am running the Mygatt-Moore Quarry in western Colorado this summer. I had been intending on doing some Fieldwork Friday post now that I have been out in the field, but have never gotten around to it. Sorry about the lack of post recently. There is a lot going on in my life at the moment that keeps me from blogging. So I thought I would give you a quick update on one of the more interesting find we have had at the quarry recently.

Tibia with dig participant for scale

A week ago this past Thursday we successfully removed a large sauropod tibia from the quarry. This is most likely from Apatosaurus, or possibly Diplodocus (but we are pretty sure at this point it’s Apato). It was initially discovered by one of our museum’s volunteers, Tom S., on July 1st as we worked the quarry. We worked hard to get it out of the ground on July 8th. Luckily for us this bone was relatively easy to excavate! It was 1100 mm long and nice and straight. We commonly get sauropod vertebra at the quarry (too many in my opinion lol), so it was nice to find something easy to excavate for once. Those freaking verts can take way to long to get out (sorry, I could rant on verts all day). The last time we removed a sauropod limb bone from the quarry in 2007 – a nice Apatosaurus fibula. It only took 8 trip participants, museum volunteers, and employees to drag the tibia on a tarp the short distance from its former 150 million year old resting place to the awaiting truck for its trip back to the museum prep lab.

Tibia encased in the field jacket and ready to be flipped

The down side of the tibia

Tom and his great find! 

It would be nice if we could get several more limb bones this summer. So far it has been dominated by sauropod verts, ribs, plenty of float and quite a few Diplodocus, Apatosaurus and Allosaurus teeth. My dream is to finally get a Mymoorapelta femur from this quarry. Fingers crossed.

Two of the teeth collected this summer

If anything else of interest pop’s up this summer I will be sure to post something about it. If you are going to be in western Colorado this summer be sure to pull off on exit 2 of I-70 and say hello!

© ReBecca K. Hunt-Foster. Please see the "Field Work Friday Rules" about the work I do and collection practices.

Only 88 days left

The Paleo Paper Challenge is on!! And there are (currently) only 88 days, 5 hours, and 11 minutes left! So, just to add to the pressure and help keep me motivated, I have installed a countdown clock on my blog (see right). I have decided to really push and try to get a paper written with my husband on the taphonomy of the Mygatt-Moore quarry. This is a quarry that numerous people have worked since it was discovered in Western Colorado in 1981. John has worked the quarry since 2001 and I have worked there since 2007. We have been tossing this paper idea around since 2007 and have not done much more than present a poster on it at GSA that fall. So, we are finally going to bite the bullet and just do it.

There is quite a bit to be done! John and I have carved up the outline for our paper, each taking sections to write and parts that we will write together. John currently is working on two other writing projects, but hopefully we will be able to get this one done. Keep your fingers crossed for us and I will post updates here as we progress.

© ReBecca K. Hunt-Foster

Fieldwork Friday #9

Yesterday John and I had a chance to visit with Dr. Jim Kirkland (Utah State Paleontologist). Jim worked in Fruita in the 1990's as the lead paleontologist for Dinomations International Society, in the same building where Dinosaur Journey is currently located. He found and participated in many important paleontological discoveries in the western Colorado area during this time. These include a Dryosaurus nesting site in the Morrison Formation, a bird skull from the Green River Formation, the first Jurassic Ankylosaur - Mymoorapelta maysi (below), along with numerous other dinosaurs from the Morrison Mygatt-Moore Quarry.

image from Gaston Design

While Jim was in town we took the opportunity to have him show us some of the classic sites he has worked, including the Dryosaurus nesting site. We hiked out the site and were happy to be able to find some additional bones.

(above) Jim and John at the site, (below) John and I at the site (picture by Jim Kirkland)

I was very excited to find a nice Dryosaurus coracoid, partial femur (pictured below) and two phalanges (toe bones). John found several small bone fragments and Jim found a nestling Dryosaurus vertebra (very small! I wish I had taken a picture of it).

Jim believes that this site was raided by mesosuchian crocodiles, which would eat the eggs/hatchlings and yearlings known from this site*. We also found a few pieces of egg shell at the site (pictured below).

This was only the second time I have seen egg shell in the Morrison Formation. The first time was at the Young Egg Site, also in Colorado (pictured below).

We continued on to prospect and locate another known site from the area (see below). We hope to be able to go out today to visit additional sites and have a chance to prospect some (if the rain will hold off).

Additional bone found in a Morrison Formation channel sandstone while prospecting.

* Kirkland, J. I. 1996. Predation of dinosaur nest by terrestrial crocodiles. Pages 124-133 in K. Carpenter, K. Hirsch, and J. Horner, editors. Dinosaur Eggs and Babies, Cambridge University Press. [free online here]

© ReBecca K. Hunt-Foster. Please see the "Field Work Friday Rules" about the work I do and collection practicies.

Mygatt-Moore Quarry Photos

These past few weeks we have been spending quite a bit of time working out in the Late Jurassic Mygatt-Moore Quarry. This quarry is located in the middle Brushy Basin Member of the Morrison Formation, in western Colorado. The most abundant dinosaur taxon at the quarry is the theropod Allosaurus (29%), which is represented by 6 individuals (5 adults, 1 juvenile); in addition, more than 190 mostly shed teeth of Allosaurus have been recovered from the site. The sauropod Apatosaurus is next most abundant (20%) with 5 individuals known from this site (3 adults, 1 sub-adult, 1 juvenile). Approximately 19% of the sample consists of bones of the ankylosaur Mymoorapelta, mostly osteoderms and lateral spines (2 individuals). The three most abundant sauropods in the Morrison Formation (Camarasaurus, Apatosaurus, and Diplodocus) also are preserved at the Mygatt-Moore Quarry, but unlike within the formation as a whole, at the MMQ Apatosaurus accounts for 85% of the sauropod bones at the site; in the formation overall, Camarasaurus is the most abundant sauropod.

I had the privilege of working at the Mygatt-Moore Quarry in 2007 as the Field Coordinator for the Museum of Western Colorado's Dinosaur Journey Museum in Fruita, Colorado. This week I have finally had a chance to load some of my pictures fron this season and last season. The majority of these pictures are from the summer of 2007 when we removed a sauropod tibia and several vertebrae (among many other things!). Some of the pictures towards the end of the section are from the end of the 2008 field season as we removed a sauropod vertebra (actually we removed two but we only have photos of one of the efforts) and prepare to remove a sauropod scapulocoracoid.

Enjoy the pictures!