Home >Documents >A densely feathered ornithomimid (Dinosauria: Theropoda...

A densely feathered ornithomimid (Dinosauria: Theropoda...

Date post:21-May-2020
Category:
View:11 times
Download:0 times
Share this document with a friend
Transcript:
  • lable at ScienceDirect

    Cretaceous Research 58 (2016) 108e117

    Contents lists avai

    Cretaceous Research

    journal homepage: www.elsevier .com/locate/CretRes

    A densely feathered ornithomimid (Dinosauria: Theropoda) from theUpper Cretaceous Dinosaur Park Formation, Alberta, Canada

    Aaron J. van der Reest*, Alexander P. Wolfe, Philip J. CurrieDepartment of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada

    a r t i c l e i n f o

    Article history:Received 18 July 2015Received in revised form18 September 2015Accepted in revised form 4 October 2015Available online xxx

    Keywords:Feathered dinosaurOrnithomimidaeOrnithomimusLate CretaceousAlberta

    Institutional abbreviations: AMNH, American MusYork, USA; BHI, Black Hills Institute of Geological ReseUSA; CMN, Canadian Museum of Nature, Ottawa, Ontof Northern Arizona, Flagstaff, Arizona, USA; ROM, RoyOntario, Canada; TMP, Royal Tyrrell Museum of PalaeoCanada; UALVP, University of Alberta LaboratoryEdmonton, Alberta, Canada.* Corresponding author.

    E-mail address: [email protected] (A.J. van de

    http://dx.doi.org/10.1016/j.cretres.2015.10.0040195-6671/© 2015 Elsevier Ltd. All rights reserved.

    a b s t r a c t

    A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous DinosaurPark Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integu-mentary structures including feathers. It is the first ornithomimid to preserve a tail bearing extensiveplumaceous feathers that are slightly more elongate in comparison to those present on the remainder ofthe body. However, the underside of the tail and the hind limb distal to the middle of the femur appeardevoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus(ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimenalso preserves the body outline around the legs, including a skin contour anterior to the femur, analogousto skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, inOrnithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as ananterior femoral web. This is the first report of such soft tissue structures in non-avian theropods. It mayindicate that the resting position of the femur was positioned more anteroventrally in ornithomimidsthan in most theropods, and in that sense may have been transitional to the situation in modern birds.

    © 2015 Elsevier Ltd. All rights reserved.

    1. Introduction

    Feathered non-avian dinosaurs are best known from the UpperJurassic and Lower Cretaceous of China, where they were firstdiscovered in 1996 (Chen, Dong, & Zhen, 1998; Hu, Hou, Zhang, &Xu, 2009; Ji, Currie, Norell, & Ji, 1998; Li et al., 2012; Norell & Xu,2005). More recently, these specimens have been augmented bydiscoveries from the Upper Jurassic of Germany (Chiappe &G€ohlich, 2010; Rauhut, Foth, Tischlinger, & Norell, 2012) and theUpper Cretaceous of western North America (Zelenitsky et al.,2012). The latter includes three relatively complete specimensassigned to Ornithomimus edmontonicus from the Dinosaur Parkand Horseshoe Canyon formations of Alberta, Canada. One juvenileand two adults each reveal feather impressions over parts of their

    eum of Natural History, Newarch, Hill City, South Dakota,ario, Canada; MNA, Museumal Ontario Museum, Toronto,ntology, Drumheller, Alberta,for Vertebrate Paleontology,

    r Reest).

    respective bodies. The juvenile preserves feather traces over theneck, body, forelimb and hind limb, whereas the less completeadult retains a halo of feather traces around the neck, back, andupper forelimb. The other and more complete adult has obliquecarbonaceous markings on the ulna and radius that are interpretedby Zelenitsky et al. (2012) as attachment traces for the calami ofpennaceous feathers; these authors suggest that the forearm ofOrnithomimus possessed a pennibrachium. Although there are noquill knobs present on TMP 1995.110.0001, this interpretation iscompatible with both ulnar quill knobs in modern birds and com-parable structures in the non-avian theropod Velociraptor (Turner,Makovicky, & Norell, 2007).

    However, because feather preservation is discontinuous andvaries considerably between each of the specimens considered byZelenitsky et al. (2012), the full extent and character of plumageadorning Ornithomimus remains incompletely resolved. In thispaper, a new specimen is described with exceptionally well pre-served integumentary structures consisting primarily of feathersand secondarily of skin traces. In addition to morphological andevolutionary implications, this specimen adds considerable insightconcerning the probable function of feathers in ornithomimid di-nosaurs. Because ornithomimids were common in the Late Creta-ceous of Alberta (Cullen, Ryan, Schr€oder-Adams, Currie, &

    mailto:[email protected]://crossmark.crossref.org/dialog/?doi=10.1016/j.cretres.2015.10.004&domain=pdfwww.sciencedirect.com/science/journal/01956671http://www.elsevier.com/locate/CretReshttp://dx.doi.org/10.1016/j.cretres.2015.10.004http://dx.doi.org/10.1016/j.cretres.2015.10.004http://dx.doi.org/10.1016/j.cretres.2015.10.004

  • A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117 109

    Kobayashi, 2013; Currie, 2005; Longrich, 2008; Makovicky,Kobayashi, & Currie, 2004), this information is broadly relevant tounderstanding these diverse and remarkable ecosystems.

    2. Materials and methods

    The new ornithomimid specimen (UALVP 52531) was discov-ered in 2009 in the northeastern sector of Dinosaur Provincial Park(Fig. 1) from the lowermost portion of the Dinosaur Park Formation(Campanian; Eberth & Hamblin, 1993). The specimenwas collected3.5 m above the boundary between the Oldman and Dinosaur Parkformations (Fig. 2), and was reposing on its left side in classicopisthotonic posture (i.e., death pose). Following removal of thejacketed specimen from the field, preparation of UALVP 52531 wasconducted using hand-operated pneumatic tools and needles.Preservation of integumentary structures was revealed alongplanes of matrix fragmentation during initial preparation. Subse-quently, detailed work surrounding bone and preserved integu-ment was performed under magnification. Preparation of theskeleton was stopped in order to preserve as much of the integu-mentary structures as possible. Standard consolidants (cyanoacry-late and Vinac dissolved in acetone) were used to stabilize boneelements during removal of the matrix, but were not applied tointegumentary structures in order to preserve delicate carbona-ceous traces. Photographs were taken with a Canon 7D digital SLRcamera and 50 mm macro lens, processed with Photoshop CS6software, and were stitched together to produce large images. Linediagrams were created from tracings of original stitched images inAdobe Illustrator CS6 with line drawings using a Wacom Intuos 5

    Fig. 1. Map of Dinosaur Provincial Park indicati

    Touch tablet. All straight-line measurements were made withdigital calipers and are accurate to ±0.01 mm; non-linear mea-surements were made with a fabric tape measure to the closestmillimeter.

    3. Results

    3.1. General description and provisional identity of UALVP 52531

    UALVP 52531 is preserved lying on its left side, the right side ofthe animal having been exposed in the field and partially destroyedby erosion. Although the skull and forelimbs were apparently lostto erosion, remaining elements include cervical vertebrae 3e6, thesecond dorsal to the 17th caudal vertebrae, the majority of the leftcostal elements, partial left scapula, left ilium, and left hind limb(Fig. 3). Of these remains, approximately 15% are surrounded byintegumentary structures, allowing comparisons with previouslydescribed feathered Ornithomimus specimens that, together, pro-duce a more complete reconstruction of plumage patterns in LateCretaceous ornithomimids. The most common integumentarystructures are unambiguous feathers comprising filaments thatrange from 25 to 87 mm in length and 0.2e0.5 mm in width, pre-served as dark carbonaceous imprints surrounding specific por-tions of the skeleton (Fig. 4).

    The femur of UALVP 52531measures 480mm in length whereasthe tibia measures 520 mm, falling within the reported ranges forOrnithomimus edmontonicus (Table 1), but 13% and 12% longer thanthe same measurements from the complete adult specimen TMP1995.110.0001 (Zelenitsky et al., 2012). This indicates UALVP 52531

    ng the discovery location of UALVP 52531.

  • Fig. 2. Stratigraphic log and position of UALVP 52531 in the lowermost 5 m of the Dinosaur Park Formation.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117110

  • Fig. 3. UALVP 52531 complete specimen. (a) Full view of articulated partial skeleton in opisthotonic death pose. (b) Line diagram of preserved material, illustrating exposed skeletalelements and inferred feathers, cartilage, body outline and skin. Abbreviations are as follow: ca, caudal vertebrae; cv, cervical vertebrae; f, femur; fl, fibula; mt IV, metatarsal IV; p,pelvic elements (ilium and sacrum); r, ribs; sc, scapula.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117 111

  • Fig. 4. Close-up of feather preservation in UALVP 52531. (a) Dense filaments above the dorsal vertebrae. (b, c) Examples of less-densely spaced but clearly branching plumage abovethe ilium.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117112

    represents a large adult. Although the lack of skull and forelimbelements make a conclusive diagnosis difficult, given that mostautapomorphies for Ornithomimus, involve the quadratojugal andmetacarpal elements (Makovicky et al., 2004). However, the distalcaudals of Ornithomimus are distinguishable from those of Stu-thiomimus by the presence of a groove on the ventral face of theprezygapophyses (Kobayashi, Makovicky, & Currie, 2006). Prepa-ration of caudals 16 and 17 revealed the presence of such grooves inUALVP 52531, allowing a positive identification of the specimen toOrnithomimus.

    Table 1Femur and tibia length measurements for UALVP 52531 (bolded) relative to other Ornith

    Taxonomic designation Specimen Femur le

    Ornithomimus sp. BHI 1266 632Ornithomimus edmontonicus CMN 12441 507Ornithomimus sp. AMNH 5884 495Ornithomimus sp. UALVP 52531 480Ornithomimus sp. MNA Pl.1762A n.a.Ornithomimus sp. CMN 8632 n.a.Ornithomimus edmontonicus ROM 851 435Ornithomimus edmontonicus TMP 95.110.1 425

    3.2. Integument of the neck and trunk

    Cervical vertebrae in UALVP 53521 are preserved within loosely-consolidated, coarse-grained sandstone that is devoid of integu-ment. However, distinct feathers are preserved along the dorsalvertebral series, where they have been compressed to adhereclosely to skeletal elements (Fig. 5). In this case, these structures arepreserved in well-consolidated, coarse-grained sandstone withextensive iron oxide cementing. Feathers around dorsal vertebrae2e7 are compressed into a single layer that is separated from the

    omimus specimens.

    ngth (mm) Tibia length (mm) Femur/tibia ratio

    700 0.90550 0.92n.a. n.a.520 0.92505 n.a.455 n.a.475 0.92465 0.91

  • Fig. 5. Dorsals 2e8 with ribs and partial left scapula of UALVP 52531. (a) Photograph showing a thin film of compressed integument overlying rib heads. The high iron content of thematrix has limited preparation of plumage in this region. (c) Line diagram illustrating the location of exposed plumage. Integument is densely arranged with anterio-posteriordirectional arrangement. Abbreviations are as follow: dtp, dorsal transverse processes; r, ribs; sc, scapula. Legend as for Fig. 3.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117 113

  • Fig. 6. Left hind limb of UALVP 52531. (a) Photograph showing integumentary struc-tures as a whitish halo around lower left leg and anterior femoral web. (b) Line dia-gram illustrating body and skin outlines around the left hind limb. The anteriorfemoral web originates from the body and inserts approximately half way down theanterior surface of the femur. Abbreviations are as follow: afw, anterior femoral web; f,femur; fl, fibula; mt IV, metatarsal IV; sac, supracetabular crest; t, tibia. Legend as forFig. 3.

    Fig. 7. Caudal plumage on UALVP 52531. (a) Photograph of feathers preserved abovethe caudal vertebrae. (b) Line diagram illustrating feathers originating at the transverseprocess of caudal vertebra VI, extending caudally, then folding over plumage origi-nating from the neural spines. These feathers splay out in a loose fan pattern, showingtheir greater length compared to the shorter surrounding feathers. Abbreviations areas follow: ca, caudal vertebrae; ch, chevrons. Legend as for Fig. 3.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117114

    bone by a thin sheet of sediment

  • A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117 115

    also preserved along the dorsal half of the preacetabular process,where they closely adhere to the surface of the bone. Integumenton the postacetabular process of the ilium is a well-defined, mul-tiple layered mat with a thickness ranging from 4.5 to 11.9 mm. Attheir bases, these feathers are dorsoventrally oriented, but curveposterodorsally more distally. A small dorsoventrally oriented

    Fig. 8. Ulna and radius of TMP 1995.110.0001. (a) Photograph of black trace marks onboth bones, interpreted as evidence for the attachment of elongated forearm feathersafter Zelenitsky et al. (2012). (b) Line drawing of the ulna (u) and radius (r) showing theexact position of trace marks. Note that no marks are observed on the proximal ordistal extremities of either bone.

    patch of feathers is preserved over the acetabulum and part of thefemoral head (Fig. 6).

    Remarkably, skin and corresponding body outlines are alsoapparent on this part of UALVP 52531, mainly as a light-colored halosurrounding portions of the skeleton (Fig. 6). Skin and feathers arevisible ventral to the preacetabular process of the ilium, originatingfrom the posterior ribs, then sharply curving ventrally to join thefemur approximately half way down the shaft. Skin in this locationis identified by a thin, slightly undulating, ferruginous layer withfeathers preserved on the surface. The total length of this skinoutline is approximately 175 mm anteroposteriorly along the cur-vature of the ventral margin. Feathers are also present posteriorlyand on the lateral surface of the proximal half of the femur. Thedistal half of the femur and the remaining lower leg are devoid offeathers. Instead, portions of the hind limb of UALVP 52531 pre-serve a distinct gray-white skin outline (Fig. 6). This halo rangesfrom 12 mm from the skeleton on the anterior face of the meta-tarsals to 76 mm on the posterior edge of the proximal end of thefemur.

    3.4. Caudal integument

    The matrix in which the caudal series is preserved changessignificantly over the length of the tail (Fig. 7). As a consequence,integument preservation varies. The five proximal caudals arepreserved within fine-grained mudstone with organic (plant)matter throughout. Here, detail of feather preservation is excellent.Caudals 6e8 are preserved within a mixture of sand and mud thatobscures the definition of individual feather filaments. Theremaining caudals (9e17) are preserved within sandstone withmore extensive iron oxide cementation, which further compro-mises the quality of feather preservation.

    Plumage preserved along the first six caudal vertebrae is ofuniform length and begins at the level of the transverse processes.The feathers curve dorsoposteriorly and terminate 69e87mm fromindividual caudal transverse processes, progressively shortening inlength distally. At the transverse process of the sixth caudal, a well-defined dense clump of feathers folds over those on the neuralspine (Fig. 7). This clump extends posterodorsally, terminating insplayed-out feathers that form a fanwith the furthest point 112mmfrom the transverse process of the ninth caudal. Integument locatedbetween caudal vertebrae 11 and 14 are visible only as a mat offilaments overlying one another. No traces of feathers are preservedbeyond caudal 14, and no feathers are encountered ventral to thetransverse processes of caudals one through nine. From caudalvertebrae 10e13, feather traces are found only up to 21 mmventrally to the transverse processes.

    4. Discussion

    UALVP 52531 augments the understanding of integumentarystructures in Ornithomimus considerably. It shows that plumage (orptilosis) was distributed as a relatively uniform, even coating overmost of the body, with the exceptions of the caudal ventrum andthe hind limbs distal to the mid-femur, which were most likelydevoid of feathers. It remains uncertain whether feathers coveredthe abdomen ventral to the gastralia. Additional specimens ofOrnithomimus, in particular TMP 1995.110.0001 (Fig. 8), indicatethat the forearm is the only part of the anatomy where the exis-tence of pterylae (defined tracts of feathers) can be confirmed.Here, at least five pterylae tracts exist on the ulna, and at least threeon the radius, restricted in both cases to the bone shafts (Fig. 8). Theaveragewidth of thesemarks is 1.2mm (Zelenitsky et al., 2012). Thegreatest width of individual feather filaments on the body of UALVP52531 is 0.4 mm laterally (Fig. 4 b and c), and may represent the

  • Fig. 9. Reconstruction of Ornithomimus showing a plumage pattern that is consistent with both UALVP 52531 and previously described feathered specimens from Alberta(Zelenitsky et al., 2012), as well as with modern ratite birds, collectively suggesting a thermoregulatory role in all cases. Artwork: Julius Csotonyi.

    A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117116

    equivalent of feather rachi. Given these attain a maximum length of~87 mm on UALVP 52531, if a similar length to width ratio existedfor the forearm feathers arranged in pterylae on TMP1995.110.0001, then a length of 260 mm can be estimated, makingthe forearm feathers approximately three times longer than bodyfeathers on Ornithomimus. The presence of forearm pterylae inOrnithomimosauria may also have important phylogenetic impli-cations, given they have not yet been reported in Tyrannosauroidea,the well-studied sister group to Maniraptoriformes (i.e.,OrnithomimosauriaþManiraptora) (Holtz, 1994), for which severalbasal representatives are known to have been feathered (Xu et al.,2004, 2012). This indicates that forearm feather pterylae repre-sent a possible synapormorphic character for Maniraptoriformes.

    UALVP 52531 is furthermore the first ornithomimid reportedwith integumentary structures on the tail, given that no caudalseries were reported for either TMP 2008.070.0001 or TMP2009.110.0001. The elongate caudal feathers of UALVP 52531 arebest preserved as a distinct clump ventral to the neural spines(Fig. 7). This indicates that feathers may have draped the tail lat-eroventrally, thus partially covering the ventral two-thirds of thetail that shows no sign of feather attachment, even in the region ofotherwise outstanding preservation. In this model, the tail wouldhave no bare skin exposed when the animal was at rest in a sittingor nesting position. Yet there is no evidence of elongated penna-ceous or plumaceous structures associated with the tail of Orni-thomimus, such as those of the basal oviraptorosaur Caudipteryx (Jiet al., 1998). On the other hand, the pygostyle of Deinocheirussuggests the possible existence of a fan of elongated caudal feathersin this atypical ornithomimosaur (Lee et al., 2014). Neither thepygostyle nor the presence of elongated caudal feathers arephylogenetically conservative characters, given their inconsistentoccurrence between and among groups.

    With respect to the non-feather integument of UALVP 52531, thepreserved skin extending from the posterior ribs to the proximal

    half of the femur resembles the knee web of birds. Skin webs arelocated in areas of high skin flexion (Cooper & Harrison, 1994), andlikely function as a way to increase mobility by allowing skin tostretch further at joints. The avian knee web is the fold of skin thatextends from the ventrolateral portion of the body to the knee,most evident when the limb is extended posteriorly (Lucas &Stettenheim, 1972). However, in Ornithomimus the skin web at-taches to the leg mid-femur and not more distally at the knee.Given this difference, coupled to the functional importance of skinwebs and analogous membranes such as patagia, the structureevident in UALVP 52531 is referred to as the anterior femoral web inorder to differentiate it from the avian knee web. This is the firstreport of this anatomical feature and one of the few reports of skinmembrane preservation in dinosaurs (Xu et al., 2015), thusproviding evidence of these structures in the basal maniraptor-iformes, and increasing the understanding of dermal evolution innon-avian theropods and their close affinity to extant neornithines.The anterior femoral web of UALVP 52531 is preserved with themiddle portion stretched dorsally into a tight arch (Fig. 6). Thisportion of the hind limb is also feathered in UALVP 52531. In thejuvenile specimen TMP 2009.110.0001, ptilosis of the pelvic andfemoral regions follow closely the contour of the thigh (Zelenitskyet al., 2012), which suggests the presence of the anterior femoralweb in a second specimen. Thus, the distal extent of femoral ptilosisin UALVP 52531 is not an artefact of preservation, but rather anindication that feathers extended no further than halfway down thefemur in Ornithomimus. This contrasts sharply other theropodsincluding Anchiornis (Hu et al., 2009), Microraptor (Li et al., 2012),and Yutyrannus (Xu et al., 2012), which have either short filamen-tous or large pennaceous feathers on the distal parts of their hindlimbs. The anterior femoral web in Ornithomimus indicates thatneutral position of the femur may have been more anteroventralthan most other non-avian theropods, suggesting a possible tran-sitional state to that in modern birds.

  • A.J. van der Reest et al. / Cretaceous Research 58 (2016) 108e117 117

    Similarities between the body forms of ornithomimids andlarge-bodied palaeognaths have been recognized for at least acentury (Osborn, 1917). With respect to Struthio camelus (ostrich),plumage of the neck is sparse but continuous, whereas feathers arecompletely absent below the femoraletibiotarsal joint (Cho, Brown,& Anderson, 1984). In contrast, in birds such as Casuarius casuarius(cassowary) and Dromaius novaehollandiae (emu), plumage extendsdistally beyond the tibiotarsaletarsometatarsal joint, but is highlyvariable on the neck. During periods of physiological heat stress,the maintenance of optimal body temperature is largely modulatedby heat loss from feather-free skin surfaces, which range from 12%in Struthio to ~18% in Dromaius and Casuarius (Phillips & Sanborn,1994). Through combinations of conductive (radiant) and convec-tive (fanning, wind) processes, up to 40% of total heat loss fromthese animals occurs from regions of exposed skin, noting that theyare endemic to warm climates such Australia and Africa. The barehind limbs and absence of feathers on the ventral surface of the tailof Ornithomimus (UALVP 53521), coupled to a lightly-featheredneck (Zelenitsky et al., 2012), can be interpreted parsimoniouslyas having served the same thermoregulatory function as in largepalaeognaths (Fig. 9).

    5. Concluding remarks

    In conclusion, while UALVP 52531 is not the first featheredornithomimid dinosaur from the Late Cretaceous of western NorthAmerica, the quality and extent of feather preservation in thisspecimen is unparalleled. As such, it provides a much stronger basisfor interpreting the most likely function of feathers in non-aviantheropods, and a much-refined perspective of the biology andecology of ornithomimids.

    Acknowledgments

    We thank Phil Bell, Michael Burns, Clive Coy, Greg Funston,Howard Gibbins, Susan Kagan, Eva Koppelhus, Derek Larson(discoverer of the specimen), and Scott Persons for assistance atvarious stages of this study. Julius Csotonyi is especially thanked forartwork. Two anonymous journal reviewers improved the pre-sentation substantially. Research was funded by the Natural Sci-ences and Engineering Research Council of Canada (DiscoveryAwards to PJC and APW) and the University of Alberta Under-graduate Research Initiative (URI). This paper is dedicated to thememory of Lynne van der Reest.

    References

    Chen, P.-J., Dong, Z.-M., & Zhen, S.-N. (1998). An exceptionally well-preservedtheropod dinosaur from the Yixian Formation of China. Nature, 391, 147e152.

    Chiappe, L. M., & G€ohlich, U. B. (2010). Anatomy of Juravenator starki (Theropoda:Coelurosauria) from the Late Jurassic of Germany. Neues Jahrbuch für Geologie

    und Pal€aontologie Abhandlungen, 258, 257e296.Cho, P., Brown, R., & Anderson, M. (1984). Comparative gross anatomy of ratites. Zoo

    Biology, 3, 133e144.Cooper, J. E., & Harrison, G. J. (1994). Dermatology. In B. W. Ritchie, G. J. Harrison, &

    L. R. Harrison (Eds.), Avian medicine: Principles and application (pp. 607e639).Lake Worth, Florida: Wingers Publishing Inc.

    Cullen, T. M., Ryan, M. J., Schr€oder-Adams, C., Currie, P. J., & Kobayashi, Y. (2013). Anornithomimid (Dinosauria) bonebed from the Late Cretaceous of Alberta, withimplications for the behavior, classification, and stratigraphy of North Americanornithomimids. PLoS One, 8, e58853.

    Currie, P. J. (2005). Theropods, including birds. In P. J. Currie, & E. B. Koppelhus(Eds.), Dinosaur Provincial Park: A spectacular ancient ecosystem revealed (pp.367e397). Bloomington, Indiana: Indiana University Press.

    Eberth, D. A., & Hamblin, A. P. (1993). Tectonic, stratigraphic, and sedimentologicsignificance of a regional discontinuity in the upper Judith River Group (BellyRiver wedge) of southern Alberta, Saskatchewan, and northern Montana. Ca-nadian Journal of Earth Sciences, 30, 174e200.

    Holtz, T. R. (1994). The phylogenetic position of the Tyrannosauridae: implicationsfor theropod systematics. Journal of Paleontology, 68, 1100e1117.

    Hu, D., Hou, L.-H., Zhang, L., & Xu, X. (2009). A pre-Archaeopteryx troodontidtheropod from China with long feathers on the metatarsus. Nature, 461,640e643.

    Ji, Q., Currie, P. J., Norell, M. A., & Ji, S.-A. (1998). Two feathered dinosaurs fromnortheastern China. Nature, 393, 753e761.

    Kobayashi, Y., Makovicky, P. J., & Currie, P. J. (2006). Ornithomimids (Theropoda:Dinosauria) from the Late Cretaceous of Alberta, Canada. Journal of VertebratePaleontology, 26(Suppl. 003), 86A.

    Lee, Y. N., Barsbold, R., Currie, P. J., Kobayashi, Y., Lee, H. J., Godefroit, P., et al. (2014).Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirusmirificus. Nature, 515, 257e260.

    Li, Q., Gao, K., Meng, Q., Clarke, J. A., Shawsky, M. D., D'Alba, L., et al. (2012).Reconstruction of Microraptor and the evolution of iridescent plumage. Science,335, 1215e1219.

    Longrich, N. (2008). A new, large ornithomimid from the Cretaceous Dinosaur ParkFormation of Alberta, Canada: implications for the study of dissociated dinosaurremains. Palaeontology, 51, 983e997.

    Lucas, A. M., & Stettenheim, P. R. (1972). Avian anatomy: Integument. Washington,DC: US Department of Agriculture.

    Makovicky, P. J., Kobayashi, Y., & Currie, P. J. (2004). Ornithomimosauria. InD. B. Weishampel, P. Dodson, & H. Osm�olska (Eds.), The Dinosauria (2nd ed., pp.137e150). Berkeley, California: University of California Press.

    Norell, M. A., & Xu, X. (2005). Feathered dinosaurs. Annual Review of Earth andPlanetary Sciences, 33, 277e299.

    Osborn, H. F. (1917). Skeletal adaptations of Ornitholestes, Struthiomimus, Tyranno-saurus. Bulletin of the American Museum of Natural History, 35, 733e771.

    Phillips, P. K., & Sanborn, A. F. (1994). An infrared, thermographic study of surfacetemperature in three ratites: ostrich, emu, and double-wattled cassowary.Journal of Thermal Biology, 19, 423e430.

    Rauhut, O. W. M., Foth, C., Tischlinger, H., & Norell, M. A. (2012). Exceptionallypreserved juvenile megalosauroid theropod dinosaur with filamentous integ-ument from the Late Jurassic of Germany. Proceedings of the National Academy ofSciences, 109, 11746e11751.

    Turner, A. H., Makovicky, P. J., & Norell, M. A. (2007). Feather quill knobs in thedinosaur Velociraptor. Science, 317, 1721.

    Xu, X., Norell, M., Kuang, X., Wang, X., Zhao, Q., & Jia, C. (2004). Basal tyrannosau-roids from China and evidence for protofeathers in tyrannosauroids. Nature,431, 680e684.

    Xu, X., Wang, K., Zhang, K., Ma, Q., Xing, L., Sullivan, C., et al. (2012). A giganticfeathered dinosaur from the Lower Cretaceous of China. Nature, 484, 92e95.

    Xu, X., Zheng, X., Sullivan, C., Wang, X., Xing, L., Wang, Y., et al. (2015). A bizarreJurassic maniraptoran theropod with preserved evidence of membranouswings. Nature, 521, 70e73.

    Zelenitsky, D. K., Therrien, F., Erickson, G. F., DeBuhr, C. L., Kobayashi, Y.,Eberth, D. A., et al. (2012). Feathered non-avian dinosaurs from North Americaprovide insight into wing origins. Science, 338, 510e514.

    http://refhub.elsevier.com/S0195-6671(15)30084-7/sref1http://refhub.elsevier.com/S0195-6671(15)30084-7/sref1http://refhub.elsevier.com/S0195-6671(15)30084-7/sref1http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref2http://refhub.elsevier.com/S0195-6671(15)30084-7/sref3http://refhub.elsevier.com/S0195-6671(15)30084-7/sref3http://refhub.elsevier.com/S0195-6671(15)30084-7/sref3http://refhub.elsevier.com/S0195-6671(15)30084-7/sref4http://refhub.elsevier.com/S0195-6671(15)30084-7/sref4http://refhub.elsevier.com/S0195-6671(15)30084-7/sref4http://refhub.elsevier.com/S0195-6671(15)30084-7/sref4http://refhub.elsevier.com/S0195-6671(15)30084-7/sref5http://refhub.elsevier.com/S0195-6671(15)30084-7/sref5http://refhub.elsevier.com/S0195-6671(15)30084-7/sref5http://refhub.elsevier.com/S0195-6671(15)30084-7/sref5http://refhub.elsevier.com/S0195-6671(15)30084-7/sref5http://refhub.elsevier.com/S0195-6671(15)30084-7/sref6http://refhub.elsevier.com/S0195-6671(15)30084-7/sref6http://refhub.elsevier.com/S0195-6671(15)30084-7/sref6http://refhub.elsevier.com/S0195-6671(15)30084-7/sref6http://refhub.elsevier.com/S0195-6671(15)30084-7/sref7http://refhub.elsevier.com/S0195-6671(15)30084-7/sref7http://refhub.elsevier.com/S0195-6671(15)30084-7/sref7http://refhub.elsevier.com/S0195-6671(15)30084-7/sref7http://refhub.elsevier.com/S0195-6671(15)30084-7/sref7http://refhub.elsevier.com/S0195-6671(15)30084-7/sref8http://refhub.elsevier.com/S0195-6671(15)30084-7/sref8http://refhub.elsevier.com/S0195-6671(15)30084-7/sref8http://refhub.elsevier.com/S0195-6671(15)30084-7/sref9http://refhub.elsevier.com/S0195-6671(15)30084-7/sref9http://refhub.elsevier.com/S0195-6671(15)30084-7/sref9http://refhub.elsevier.com/S0195-6671(15)30084-7/sref9http://refhub.elsevier.com/S0195-6671(15)30084-7/sref10http://refhub.elsevier.com/S0195-6671(15)30084-7/sref10http://refhub.elsevier.com/S0195-6671(15)30084-7/sref10http://refhub.elsevier.com/S0195-6671(15)30084-7/sref11http://refhub.elsevier.com/S0195-6671(15)30084-7/sref11http://refhub.elsevier.com/S0195-6671(15)30084-7/sref11http://refhub.elsevier.com/S0195-6671(15)30084-7/sref12http://refhub.elsevier.com/S0195-6671(15)30084-7/sref12http://refhub.elsevier.com/S0195-6671(15)30084-7/sref12http://refhub.elsevier.com/S0195-6671(15)30084-7/sref12http://refhub.elsevier.com/S0195-6671(15)30084-7/sref13http://refhub.elsevier.com/S0195-6671(15)30084-7/sref13http://refhub.elsevier.com/S0195-6671(15)30084-7/sref13http://refhub.elsevier.com/S0195-6671(15)30084-7/sref13http://refhub.elsevier.com/S0195-6671(15)30084-7/sref14http://refhub.elsevier.com/S0195-6671(15)30084-7/sref14http://refhub.elsevier.com/S0195-6671(15)30084-7/sref14http://refhub.elsevier.com/S0195-6671(15)30084-7/sref14http://refhub.elsevier.com/S0195-6671(15)30084-7/sref15http://refhub.elsevier.com/S0195-6671(15)30084-7/sref15http://refhub.elsevier.com/S0195-6671(15)30084-7/sref16http://refhub.elsevier.com/S0195-6671(15)30084-7/sref16http://refhub.elsevier.com/S0195-6671(15)30084-7/sref16http://refhub.elsevier.com/S0195-6671(15)30084-7/sref16http://refhub.elsevier.com/S0195-6671(15)30084-7/sref16http://refhub.elsevier.com/S0195-6671(15)30084-7/sref17http://refhub.elsevier.com/S0195-6671(15)30084-7/sref17http://refhub.elsevier.com/S0195-6671(15)30084-7/sref17http://refhub.elsevier.com/S0195-6671(15)30084-7/sref18http://refhub.elsevier.com/S0195-6671(15)30084-7/sref18http://refhub.elsevier.com/S0195-6671(15)30084-7/sref18http://refhub.elsevier.com/S0195-6671(15)30084-7/sref19http://refhub.elsevier.com/S0195-6671(15)30084-7/sref19http://refhub.elsevier.com/S0195-6671(15)30084-7/sref19http://refhub.elsevier.com/S0195-6671(15)30084-7/sref19http://refhub.elsevier.com/S0195-6671(15)30084-7/sref20http://refhub.elsevier.com/S0195-6671(15)30084-7/sref20http://refhub.elsevier.com/S0195-6671(15)30084-7/sref20http://refhub.elsevier.com/S0195-6671(15)30084-7/sref20http://refhub.elsevier.com/S0195-6671(15)30084-7/sref20http://refhub.elsevier.com/S0195-6671(15)30084-7/sref21http://refhub.elsevier.com/S0195-6671(15)30084-7/sref21http://refhub.elsevier.com/S0195-6671(15)30084-7/sref22http://refhub.elsevier.com/S0195-6671(15)30084-7/sref22http://refhub.elsevier.com/S0195-6671(15)30084-7/sref22http://refhub.elsevier.com/S0195-6671(15)30084-7/sref22http://refhub.elsevier.com/S0195-6671(15)30084-7/sref23http://refhub.elsevier.com/S0195-6671(15)30084-7/sref23http://refhub.elsevier.com/S0195-6671(15)30084-7/sref23http://refhub.elsevier.com/S0195-6671(15)30084-7/sref24http://refhub.elsevier.com/S0195-6671(15)30084-7/sref24http://refhub.elsevier.com/S0195-6671(15)30084-7/sref24http://refhub.elsevier.com/S0195-6671(15)30084-7/sref24http://refhub.elsevier.com/S0195-6671(15)30084-7/sref25http://refhub.elsevier.com/S0195-6671(15)30084-7/sref25http://refhub.elsevier.com/S0195-6671(15)30084-7/sref25http://refhub.elsevier.com/S0195-6671(15)30084-7/sref25

    A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada1. Introduction2. Materials and methods3. Results3.1. General description and provisional identity of UALVP 525313.2. Integument of the neck and trunk3.3. Integument of the appendicular skeleton3.4. Caudal integument

    4. Discussion5. Concluding remarksAcknowledgmentsReferences

of 10/10
A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada Aaron J. van der Reest * , Alexander P. Wolfe, Philip J. Currie Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada article info Article history: Received 18 July 2015 Received in revised form 18 September 2015 Accepted in revised form 4 October 2015 Available online xxx Keywords: Feathered dinosaur Ornithomimidae Ornithomimus Late Cretaceous Alberta abstract A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integu- mentary structures including feathers. It is the rst ornithomimid to preserve a tail bearing extensive plumaceous feathers that are slightly more elongate in comparison to those present on the remainder of the body. However, the underside of the tail and the hind limb distal to the middle of the femur appear devoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus (ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimen also preserves the body outline around the legs, including a skin contour anterior to the femur, analogous to skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, in Ornithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as an anterior femoral web. This is the rst report of such soft tissue structures in non-avian theropods. It may indicate that the resting position of the femur was positioned more anteroventrally in ornithomimids than in most theropods, and in that sense may have been transitional to the situation in modern birds. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Feathered non-avian dinosaurs are best known from the Upper Jurassic and Lower Cretaceous of China, where they were rst discovered in 1996 (Chen, Dong, & Zhen, 1998; Hu, Hou, Zhang, & Xu, 2009; Ji, Currie, Norell, & Ji, 1998; Li et al., 2012; Norell & Xu, 2005). More recently, these specimens have been augmented by discoveries from the Upper Jurassic of Germany (Chiappe & Gohlich, 2010; Rauhut, Foth, Tischlinger, & Norell, 2012) and the Upper Cretaceous of western North America (Zelenitsky et al., 2012). The latter includes three relatively complete specimens assigned to Ornithomimus edmontonicus from the Dinosaur Park and Horseshoe Canyon formations of Alberta, Canada. One juvenile and two adults each reveal feather impressions over parts of their respective bodies. The juvenile preserves feather traces over the neck, body, forelimb and hind limb, whereas the less complete adult retains a halo of feather traces around the neck, back, and upper forelimb. The other and more complete adult has oblique carbonaceous markings on the ulna and radius that are interpreted by Zelenitsky et al. (2012) as attachment traces for the calami of pennaceous feathers; these authors suggest that the forearm of Ornithomimus possessed a pennibrachium. Although there are no quill knobs present on TMP 1995.110.0001, this interpretation is compatible with both ulnar quill knobs in modern birds and com- parable structures in the non-avian theropod Velociraptor (Turner, Makovicky, & Norell, 2007). However, because feather preservation is discontinuous and varies considerably between each of the specimens considered by Zelenitsky et al. (2012), the full extent and character of plumage adorning Ornithomimus remains incompletely resolved. In this paper, a new specimen is described with exceptionally well pre- served integumentary structures consisting primarily of feathers and secondarily of skin traces. In addition to morphological and evolutionary implications, this specimen adds considerable insight concerning the probable function of feathers in ornithomimid di- nosaurs. Because ornithomimids were common in the Late Creta- ceous of Alberta (Cullen, Ryan, Schroder-Adams, Currie, & Institutional abbreviations: AMNH, American Museum of Natural History, New York, USA; BHI, Black Hills Institute of Geological Research, Hill City, South Dakota, USA; CMN, Canadian Museum of Nature, Ottawa, Ontario, Canada; MNA, Museum of Northern Arizona, Flagstaff, Arizona, USA; ROM, Royal Ontario Museum, Toronto, Ontario, Canada; TMP, Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada; UALVP, University of Alberta Laboratory for Vertebrate Paleontology, Edmonton, Alberta, Canada. * Corresponding author. E-mail address: [email protected] (A.J. van der Reest). Contents lists available at ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes http://dx.doi.org/10.1016/j.cretres.2015.10.004 0195-6671/© 2015 Elsevier Ltd. All rights reserved. Cretaceous Research 58 (2016) 108e117
Embed Size (px)
Recommended