Vertebrate Ichnopathology: Pathologies Inferred from Dinosaur Tracks and Trackways from the Mesozoic
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Ichnos An International Journal for Plant and Animal Traces ISSN: 1042-0940 (Print) 1563-5236 (Online) Journal homepage: http://www.tandfonline.com/loi/gich20 Vertebrate Ichnopathology: Pathologies Inferred from Dinosaur Tracks and Trackways from the Mesozoic Richard T. McCrea, Darren H. Tanke, Lisa G. Buckley, Martin G. Lockley, James O. Farlow, Lida Xing, Neffra A. Matthews, Charles W. Helm, S. George Pemberton & Brent H. Breithaupt To cite this article: Richard T. McCrea, Darren H. Tanke, Lisa G. Buckley, Martin G. Lockley, James O. Farlow, Lida Xing, Neffra A. Matthews, Charles W. Helm, S. George Pemberton & Brent H. Breithaupt (2015) Vertebrate Ichnopathology: Pathologies Inferred from Dinosaur Tracks and Trackways from the Mesozoic, Ichnos, 22:3-4, 235-260 To link to this article: http://dx.doi.org/10.1080/10420940.2015.1064408 Published online: 11 Sep 2015. Submit your article to this journal View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=gich20 Download by: [University of Alberta] Date: 11 September 2015, At: 20:40 Ichnos, 22:235–260, 2015 Copyright Ó Taylor & Francis Group, LLC ISSN: 1042-0940 print / 1563-5236 online DOI: 10.1080/10420940.2015.1064408 Vertebrate Ichnopathology: Pathologies Inferred from Dinosaur Tracks and Trackways from the Mesozoic Richard T. McCrea1,2, Darren H. Tanke3, Lisa G. Buckley1,4, Martin G. Lockley5, James O. Farlow6, Lida Xing7, Neffra A. Matthews8, Charles W. Helm1, S. George Pemberton2, and Brent H. Breithaupt9 1Peace Region Palaeontology Research Centre, Tumbler Ridge, British Columbia, Canada 2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada 3Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada 4Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada 5Dinosaur Trackers Research Group, University of Colorado, Denver, Colorado, USA 6Department of Geosciences, Purdue University, Fort Wayne, Indiana, USA 7School of Earth Sciences and Resources, China University of Sciences, Beijing, China 8Bureau of Land Management, Denver, Colorado, USA 9Wyoming State Office, Bureau of Land Management, Cheyenne, Wyoming, USA INTRODUCTION Literature concerning dinosaur footprints or trackways Over the course of the past few decades, there has been a exhibiting abnormal gait or morphology reflecting pathology marked increase in the literature of pathology of dinosaurs (ichnopathology) is rare. We report on a number of Jurassic and Cretaceous occurrences of theropod footprints from western (e.g., Tanke and Rothschild, 2002 and references therein). North America with unusual morphologies interpreted herein as However, the literature on inferred pathology from dinosaur examples of inferred pathologies, or ichnopathologies. The tracks and trackways (ichnopathology) has not seen a corre- majority of ichnopathologies are primarily manifested in the sponding increase. Reports on ichnopathology in dinosaurs digit impressions and include examples of swelling, extreme have been infrequent, with perhaps less than one paper pub- curvature, dislocation or fracture, and amputation. A number of occurrences are single tracks on ex situ blocks with substantial lished per decade since the beginning of modern studies of deformation (inferred dislocation or fracture), or absence of a dinosaur traces in the early 19th century. It is possible that single digit impression. Two occurrences are from in situ natural reports of ichnopathology have not kept pace with reports of mould trackways, one of which is a lengthy trackway of a pathologies on osteological specimens due to the various influ- presumed allosauroid with no noticeable deformation of the ences of track-bearing substrate, the behavior of the track- digits or feet but with strong inward rotation of the left Downloaded by [University of Alberta] at 20:40 11 September 2015 footprint toward the midline and a pronounced, waddling limp. maker, as well as a range of taphonomic factors that make The other is a tyrannosaurid trackway consisting of three such interpretations difficult. The sparse publication record of footprints (one right, two left) with the two left prints exhibiting ichnopathology may also be a reflection of the cautious repetitive ichnopathology of a partially missing Digit II approach ichnologists employ when interpreting phenomena impression. related to tracks. Even with a restrained approach toward footprint and track- Keywords Dinosaur tracks, Amputation, Antalgic gait, Compen- way interpretation, some dinosaur tracks and trackways exhibit sated gait, Jurassic, Cretaceous, Ichnopathology, Later- morphologies that have defied explanation by conventional ality, Irregular gait, Limping gait, Shuffling gait, Waddling gait behaviors of the trackmaker, or by the physical and dynamic qualities of the track surface, both pre- and post-burial. This article discusses previous reports of dinosaur ichnopa- thology with reinterpretations where such is warranted. Sev- Address correspondence to Richard T. McCrea, Peace Region eral recent and new reports of dinosaur ichnopathologies are Palaeontology Research Centre, Box 1540, Tumbler Ridge, BC, V0C 2W0, Canada. E-mail: [email protected] described, from sites in the Jurassic of China and the Creta- Color versions of one or more figures in this article can be found ceous of North America. A number of criteria are proposed online at www.tandfonline.com/gich. that will aid in the interpretation of ichnopathologies 235 236 R. T. MCCREA ET AL. FIG. 1. Antipus bifidus trackway with missing digit from the Early Jurassic of Connecticut. Left image modified from Hitchcock, 1858 plate 48, figure 10. Right image modified from Hitchcock, 1858, plate 36, fig. 8. The right image has been scaled and rotated to match the orientation of the left image. MATERIALS AND METHODS confusion about the bifid footprint with associated tail impres- A series of overlapping photographic images were taken for sion, which seemed to be characteristic of “lizards,” but he photogrammetric imaging with a DSLR Camera (Canon EOS was unable to reconcile the two digit prints with the anatomy 7D) and rendered into 3D models using Agisoft Photoscan of any known “lizard.” In his description of Antipus bifidus Professional (v 1.0.4) and Cloud Compare (v 2.5.3). Hitchcock (1858) did not entertain the possibility that this print might have been from a track-maker that was missing a digit. Lull (1953) mentions the didactyl character of Antipus PREVIOUS REPORTS OF ICHNOPATHOLOGY bifidus, but aside from referring to it as “a very questionable The literature of dinosaur ichnites and trackways demon- species” he did not consider the possibility of this print being strating various pathological conditions was reviewed by pathological. Since an entire lateral digit impression is missing Tanke and Rothschild (2002), and we summarize a few of it is likely that this could be the first legitimate example of an these cases here. Hitchcock (1844) described a trackway as ichnopathology. Sauroidichnites abnormis, a short trackway of four small, tri- Inferred pedal digit loss in the right foot of an otherwise dactyl prints from the Early Jurassic (Hitchcock, 1844, normal Eubrontes trackway from the Newark Supergroup figs. 6–8). Hitchcock (1844) thought that while the midlines of (Late Triassic–Early Jurassic) was reported by Abel (1935). the two left prints were oriented toward the direction of travel, The missing digit impression was repeated in the trackway the two right prints were strongly rotated toward the trackway (Fig. 2) making this a convincing example of ichnopathology. midline by nearly 45 indicating an injury to the right foot. We suggest that trackways with one or more visible, repeti- Downloaded by [University of Alberta] at 20:40 11 September 2015 Upon examination of Hitchcock’s illustration of the Sauroi- tive pathologies, but with a nearly normal gait (no, or minimal dichnites abnormis trackway (Hitchcock, 1844, fig. 8), it trace of a limp), such as the Eubrontes trackway reported by appears that the midline of print 1 (left) is oriented toward the Abel (1935) be classified as examples of Compensated Gait. direction of travel as Hitchcock initially described. Print 2 (right) of this trackway is strongly in turned toward the mid- line of the trackway as is print 4 (right). However, print 3 (left) is noticeably rotated toward the trackway midline, not as strongly as prints 2 and 4 though. It is likely that this track- way is one of the first described examples of ichnopathology. Fourteen years later, Hitchcock (1858) reported on fossil tracks from the Early Jurassic of Connecticut and illustrated a trackway of a quadrupedal animal (pl. 36, fig. 8 and pl. 48, fig. 10) that exhibited only two digit impressions on the fore- FIG. 2. A Late Triassic – Early Jurassic Eubrontes isp. trackway from the foot (Fig. 1) which he described as Antipus bifidus. In his Newark Supergroup with a missing digit (Abel, 1935). Figure modified from description of Antipus bifidus, Hitchcock (1858) expressed Lockley, 1991. Scale bar D 1 metre VERTEBRATE ICHNOPATHOLOGY 237 Such trackways demonstrate that the track-making animal has adapted to, or compensated for the visible injury and its loco- motion is very close to normal. Tucker and Burchette (1977, p. 198) described prosauropod (Anchisauripus) ichnites from the Triassic (Norian) of south Wales with a “....distinctive malformation of digit III....”