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Scientific Papers

Given the central role of scientific research in MRF, we have created a section for all of the peer reviewed scientific papers produced by MRF staff or papers using MRF material. Many MRF volunteers helped excavate many of the localities that are now being published on. There is a brief summary of each paper. A pdf of the paper can be downloaded by clicking on the reference.

Click on an item to read the full paper.

• A New Box Turtle from the Miocene/Pliocene Boundary (Latest Hemphillian) of Oklahoma and A Refined Chronology of Box Turtle Diversification

  Journal of Paleontology (2012)
  Walter G. Joyce, Andrea Petričević, Tyler R. Lyson and Nicholas J. Czaplewski

• MicroRNAs support a turtle + lizard clade

  Biology Letters (2011)
  Tyler R. Lyson, Erik A. Sperling, Alysha M. Heimberg, Jacques A. Gauthier, Benjamin L. King and Kevin J. Peterson

• Dinosaur extinction: closing the ‘3 m gap’

  Biology Letters (2011)
  Tyler R. Lyson, Antoine Bercovici, Stephen G. B. Chester, Eric J. Sargis, Dean Pearson and Walter G. Joyce

• Cranial Anatomy and Phylogenetic Placement of the Enigmatic Turtle Compsemys victa Leidy, 1856

  Journal of Paleontology (2011)
  Tyler R. Lyson and Walter G. Joyce

• Boremys (Testudines, Baenidae) from the latest Cretaceous and early Paleocene of North Dakota: an 11-million-year range extension and an additional K/T survivor

  Journal of Vertebrate Paleontology (2011)
  Tyler R. Lyson, Walter G. Joyce, Georgia E. Knauss and Dean A. Pearson

• Pangshura tatrotia, a new species of pond turtle (Testudinoidea) from the Pliocene Siwaliks of Pakistan

  Journal of Systematic Palaeontology (2010)
  Walter G. Joyce and Tyler R. Lyson

  Summary
  We describe a new species of fossil testudinoid from the Indian subcontinent, Pangshura tatrotia sp. nov., and suggest a new clade name, Palatochelydia, for the monophyletic assemblage of South Asian turtles to which it belongs. A combined analysis using recent molecular data and an updated morphological dataset confidently places P.tatrotia as sister to the extant turtle P. tecta. The holotype specimen is unique relative to most previously described palatochelydian material in that it is associated with good quality locality information.

• Transitional fossils and the origin of turtles

  Biology Letters (2010)
  Tyler R. Lyson, Gabe S. Bever, Bhart-Anjan S. Bhullar, Walter G. Joyce and Jacques A. Gauthier

  Summary
  The origin of turtles is one of the most conten- tious issues in systematics with three currently viable hypotheses: turtles as the extant sister to (i) the crocodile–bird clade, (ii) the lizard– tuatara clade, or (iii) Diapsida (a clade composed of (i) and (ii)). We reanalysed a recent dataset that allied turtles with the lizard–tuatara clade and found that the inclusion of the stem turtle Proganochelys quenstedti and the 'parareptile' Eunotosaurus africanus results in a single over-riding morphological signal, with turtles outside Diapsida. This result reflects the importance of transitional fossils when long branches separate crown clades, and highlights unexplored issues such as the role of topological congruence when using fossils to calibrate molecular clocks.

• Spatial niche partitioning in dinosaurs from the latest Cretaceous (Maastrichtian) of North America

  Proceedings of the Royal Society (2010)
  Tyler R. Lyson and Nicholas R. Longrich

  Summary
  We examine patterns of occurrence of associated dinosaur specimens (n = 343) from the North American Upper Cretaceous Hell Creek Formation and equivalent beds, by comparing their relative abundance in sandstone and mudstone.

• A neglected lineage of North American turtle fills a major gap in the fossil record

  Palaeontology (2010)
  Walter G. Joyce and Tyler R. Lyson

  Summary
  The fossil record of the two primary subclades of softshell turtles (Trionychidae) is exceedingly asymmetric, as a result of a ghost range of total clade Cyclanorbinae that is estimated at 80 Ma. Herein, we present the first phylogenetic analysis of Trionychidae that includes a representative of the poorly studied taxon Plastomenidae, which is known from the Campanian to Eocene of North America.

• A new kinosternoid from the Late Cretaceous Hell Creek Formation of North Dakota and Montana and the origin of the Dermatemys mawii lineage

  Paläontologische Zeitschrift (2010)
  Georgia E. Knauss, Walter G. Joyce, Tyler R. Lyson and Dean Pearson

  Summary
  A nearly complete turtle shell from the Late Cretaceous (Maastrichtian) Hell Creek Formation of Slope County, North Dakota, represents the most complete remains to date of a Mesozoic kinosternoid turtle and a new species, Hoplochelys clark nov. sp. The new taxon is diagnosable from other representatives of Hoplochelys by the plesiomorphic placement of the humeral/femoral sulcus behind the hyo/hypoplastral suture and the autapomorphic development of an interrupted median (neural) keel.

• A new baenid turtle from the upper Cretaceous (Maastrichtian) Hell Creek Formation of North Dakota and a preliminary taxonomic review of Cretaceous baenidae

  Journal of Vertebrate Paleontology (2010)
  Tyler R. Lyson and Walter G. Joyce

  Summary
  A fragmentary skull from the Hell Creek Formation (Maastrichtian) of southwestern North Dakota represents a new taxon of baenid turtle named herein Gamerabaena sonsalla. The length of the frontals, jugal contribution to the labial ridge, and convex contact between the vomer and the pterygoids indicate its affinities with the clade Palatobaena, but the new taxon clearly lacks the great posterior expansion of the triturating surface, complete absence of a lingual ridge, subrectangular skull, and wide angle between the maxillae that diagnose Palatobaena spp.

• Turtles all the way down: loggerheads at the root of the chelonian tree

  Evolution and Development (2009)
  Tyler Lyson and Scott F. Gilbert

  Summary
  This paper discusses the amazing turtle with teeth and half a shell from China, Odontochelys semitestacea. This amazing turtle surprised the scientific community and reopened up several important questions regarding the origin of turtles, the origin of the turtle shell, and their original paleoecology (aquatic or terrestrial).

• A Revision of Plesiobaena (Testudines: Baenidae) and an Assessment of Baenid Ecology Across the K/T Boundary

  Journal of Paleontology (2009)
  Tyler R. Lyson and Walter G. Joyce

  Summary
  A new species of baenid turtle is described from the Hell Creek Formation. Material of this new species, Peckemys brinkman, was found at MRF's Turtle Graveyard locality. This locality is unusual in that it represents a true snapshot in time (i.e. it is constrained both temporally and spatially). The locality is the most diverse fossil turtle assemblage. Much of the material described in this paper was found by MRF volunteers. The paper discusses the diversity of turtles found at this locality as well as the number of baenid turtles that go extinct at the K/T boundary. Baenid turtles do surprisingly well across the boundary, with seven of nine baenids surviving into the Paleocene. Interestingly, four of the seven survivors are interpreted as having a mollusk and snail type diet.

• A New Species of Palatobaena (Testudines: Baenidae) and a Maximum Parsimony and Bayesian Phylogenetic Analysis of Baenidae

  Journal of Paleontology (2009)
  Tyler R. Lyson and Walter G. Joyce

  Summary
  This is the first of a series of papers on Marmarth Research Foundation's Turtle Graveyard and Turtle Ridge localities. These localities are the world's most diverse and largest fossil turtle quarries. They have produced a number of new species, including the one described in this paper: Palatobaena cohen. This enigmatic turtle was named after MRF board of director and longtime volunteer Steven Cohen. The paper discusses the geology of the Turtle Graveyard locality, a detailed description of the skull and shell, and a phylogenetic analysis of the group of turtle to which Pa. cohen belongs, Baenidae. Hundreds of MRF volunteers have helped excavate this locality and found the material described in this paper including John Akerly (shell), Pam Hollocher (shell), Lou Tremblay (skull and lower jaw), and Norman Gardiner (skull).

• Evolution of the Respiratory System in Nonavian Theropods: Evidence from Rib and Vertebral Morphology

  The Anatomical Record (2009)
  Emma R. Schachner, Tyler R. Lyson, and Peter Dodson

  Summary
  This study analyzes rib and vertebral anatomy of carnivorous dinosaurs in order to help determine the type of respiratory system present in carnivorous dinosaurs. Did carnivorous dinosaurs have a flow-through ventilation system as in birds? Or did they have a more crocodilian-like hepatic-piston respiratory system? The study shows that a crocodilian-like hepatic-piston lung would be functionally and biomechanically untenable and that carnivorous dinosaurs share respiratory anatomical characters with birds (i.e. air sacs) and likely had a more bird-like respiratory system.

• Mineralized soft-tissue structure and chemistry in a mummified hadrosaur from Hell Creek Formation, North Dakota

  Proceedings of The Royal Society B (2009)
  Phillip L. Manning, Peter M. Morris, Adam McMahon, Emrys Jones, Andy Gize, Joe H. S. Macquaker, George Wolff, Anu Thompson, Jim Marshall, Kevin G. Taylor, Tyler Lyson, Simon Gaskell, Onrapak Reamtong, William I. Sellers, Bart E. van Dongen, Mike Buckley and Roy A. Wogelius

  Summary
  This is the first of a series of papers on the mummified dinosaur "Dakota." This paper was selected by Discover Magazine as one of the top 100 best scientific papers of 2009 (ranking 46). The paper goes through a number of geochemical analyses in search of original biomolecules from "Dakota." In addition, the paper discusses how "Dakota" was preserved and describes the 3-D preservation of the skin.

• Virtual Palaeontology: Gait Reconstruction of Extinct Vertebrates Using High Performance Computing

  Palaeontologia Electronica (2009)
  William I. Sellers, Phillip L. Manning, Tyler R. Lyson, Kent Stevens, and Lee Margetts

  Summary
  Were hadrosaur dinosaurs running on two or four legs at top speed? This paper uses computer simulations to try and address this question. An 8000 core computer was used to produce mechanically and physiologically plausible gaits and trackway patterns for an Edmontosaur annectens dinosaur. Galloping was determined to be the most plausible and fastest (16 ms-1) gait, followed by bipedal running (14ms-1).

  Watch the Edmontosaur gallop (mov, 11MB), run (mov, 10.5MB), and even hop (mov, 8MB)!

• Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming

  Bulletin of the Peabody Museum of Natural History (2009)
  Walter G. Joyce, Ariel Revan, Tyler R. Lyson, and Igor G. Danilov

  Summary
  Two new species of soft-shelled (Trionychidae) turtles are described and their paleoecology discussed. The subgroup of trionychids described, Plastomenidae, are unusual in that they have a well-ossified bottom shell (plastron). The group is thought to be part of the lineage that gave rise to modern day flap shelled turtles (Cyclanorbinae).