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Paleontological Contributions THE UNlVERSI1Y OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS March 15, 2000 Number 13 REMARKABLE NEW BIRDLIKE DINOSAUR (THEROPODA: MANIRAPTORA) FROM THE UPPER CRETACEOUS OF MONTANA David A. Burnham,! Kraig L. Derstler,2 Philip J. Currie,:l Robert T. Bakker,4 Zhonghe Zhou,' and John H. Ostrom6 ''','Iliral I liston' :VlliSClIlll 'lIlel Bioeli\'crsitl Rcsearch (:el1leL thelle Ilall, The 11l1iH".sin or Kmsas, Lnnl'lln', KlI1sas (,tiO-l:i, I() ........ (lr(f!' LdcOll,C( .ukan ..... cdll: ~ UCP<lrtllIl'll t of (~c()l()h:n. and (~e()pli:·sic.... , l'11 i\ cr"i tY 01 1\' ('\\ (hlcan~, .:\ cw (Jr1t'an .... Lou isiall<l 7014H. kell'l'sl!l'((J)ul1o,eelu: 'Ko\'al T"'rell Musculll 01 Pabeolltolo!!:l. Bo, ':iOO. llnllllildler, Alherta TO) OVO, Callaela, pllilipeurtrilllcd.,!!:OI.ah.ca: 'florida Atlal1tic L'ni\l'rsill, Florida Institllt,· 01 l'ak'Hl1oloh'Y at thc Cralcs :vlttSt'lll1] ot '\rchaeolog' and :\atur:d Iliston, ~S] SOllth Federal IIiglm:n , Dania Beach, Florida :noo 1: "Institutc of \ ntehr:]te l'aleO!][oloh'Y ancl P:deoal1lhropoloh'Y. Ghinest' Acadel1l1 0/ Scicnces. PO Box (;,1'1, lkijil1g 100041, China. Ihonghcl(]lcah.nct; "l'caho,!I \[\!SCUlll of :\alural His!on. Valt' l·niICTsi(l. PO Bo" :!('SIS. "JCII Ha\'cl1, Conneclicul O(ic,:!O . .i.bstmrt.-'v\'t: describe a small drmnaeosauricl dillosaur, BambimjJtorjtinberr;i n. gt:n. and n. sp.. bast'd upon a nearly complt:te fossil skeleton from the Two \ledicine Formation (Upper Cretaceous) of :'vlontana. \\'idt:h knm\n as Bambi, this skeleton is a well-prt:sent:d suhadult that is about 75 pncent adult size. Larger bones hom the same locality suggest little anatomical ch~lnge during late ontogeny. While this species fits the dromaeosaurid gestalt, il also shares anumbn of features "ith early hirds. INTRODUCTION us to fit the hones and reconstruct the animal's po,ture \\ith some confidence. In September 1993, Wes Linster discoyered the fossil Scauerecl bones tilllnd within the same deposit appar­ remains of a small theropod in the Two Medicine Forma­ ently came from othtT incliyiduals of the same species. tion near Bynum, :'vlontana. Within a few days, Wes and his Most came from animals approximateh- one third largn family eXG1yated the skeleton and began preparing the than tilt: llOlotype. bOlles. They also began calling their find Bamhi, a nick­ The species is allied with such dromaeosaurid thfTopods name that has since become widely nsed. The family con­ as LJeillollYc!WS Ostrom (l909a) and l','{()cirnjJ(o} Osborn tacted the senior author in 2\)m'ember 1995 to consen'e (1924). We initially belie\'ed it to be conspecific with a and prepare the specimen. The small size and fragile na­ dromaeosaurid already reported from the T\\o Medicine ture ofthe bones subsequen tho required thousands of hours Formation, Sallronzitho{estn {I/llp;stoni Sues (1978) of micropreparation. (\'arricchio &: Currie, 1991; Burnham. Oerstlel', and Linster, The discmen of this fossil was announced in a prelimi­ 1997). We demonstrate herein that it differs from all de­ nan paper (Burnham, Derstler. ~lIld Linster, 1997). scribed theropods including S. {a IIgstolli. Some of these Ft:duccia (1999) figured and bridh discussed the skeleton differences may relate to the subadult nature of the fossil, using information proYided b, the senior author. but there arc suUicient difTerences to t:rect a new taxon: The skeleton is more than 90-percent complete and Bl/mbirajJ(orji'inbNf.,ri n, gen. and n. sp. well preserYed. Most of the bones haye retained their origi­ In this paper we descrilw the new species, otfer some nal shapes and articular surh1ces. Some articulation infor­ initial anatomical obseITations. and point Oul some 01 its mation has been lost, but the excellent preselyation allows more o])\'ious birdli ke features. Copyright .{) 2000, The University of Kansas, Paleontological Institute 2 The University of Kansas Paleontological Contributions Institutional abbreviations cited: FIP, Florida Institute Table 1. Lengths (in mm) of selected elements of the of Paleontology, Dania Beach, Florida; KUVP, The Univer- holotype Bambiraptor feinbergi (FIP 001) and Bambiraptor sity of Kansas Natural History Museum and Biodiversity adult bones (new). Research Center, Lawrence, Kansas; SMM, The Science skull 125* Museum of Minnesota, St. Paul, Minnesota. mandible 121* 87 right scapula SYSTEMATIC PALEONTOLOGY left coracoid 40 left sternum 69 Terminology follows Weishampel, Dodson, and five sacral vertebrae 60 Osmélska (eds., 1990), except that the semilunate carpal is left humerus 105 not referred to as the radiale. left ulna 95 left metacarpal II 48 DINOSAURIA Owen, 1842 three phalanges of left manual digit II 85 left ilium 85 THEROPODA Marsh, 1881 left ischium 52 MANIRAPTORA Gauthier, 1986 left pubis 105 left femur 119 DROMAEOSAURIDAE Matthew and Brown, 1922 left tibia 168 BAMBIRAPTOR n. gen. left metatarsal III 78 four phalanges of left pedal digit III 76 Type species.—Bambiraptor feinbergi n. sp. adult femur 170 Diagnosis.—Jugal with row of foramina along ventral adult humerus 145 margin; scapula with large, medially directed acromion; adult tibia 225 distinct, short scapulocoracoid suture; coracoid with neck adult metatarsal III 105 or peduncle forming part of glenoid; coracoid foramen *estimated. absent; 13 dentary teeth, 9 maxillary teeth; ratio of hu- merus plus ulna to the femur large (H+U/F = 1.68); pubis The holotype includes two elements seldom recorded with distal shaft and boot rotated posterodorsally; ischium in theropods. The first is a hyoid. This slender rod is 3 cm with small proximal dorsal process; femur strongly recurved long and nearly straight. It was preserved in the skull laterally and posteriorly. block, below the basicranium and between the mandibular Remarks.—Genus presently contains a single species. condyles of the two quadrates. The other is the right stapes. A portion of this delicate bone lay in position against the BAMBIRAPTOR FEINBERGI n. sp. right exoccipital. Figure 1-8 A paraquadratic fenestra is framed by a reduced, for- Velociraptor sp. cf. V. langstoni (Sues); Burnham, Derstler, wardly deflected bar of bone. This bar is formed by the and Linster, 1997, p. 75. ascending process of the quadratojugal and the descend- Velociraptor Feduccia, 1999, p. 380. ing process of the squamosal. It is slender and nearly Diagnosis.—As for genus. threadlike in B. feinbergi. The quadratojugal portion of this Description.—The holotype skeleton of Bambiraptor bar is curved. The quadrate has rostrolateral flanges nearly feinbergi has an estimated length of one meter. It is a lightly as long as the quadrate is high. built theropod (Table 1), with proportions more similar to In lateral view, the mandible is nearly parallel sided. those of Archaeopteryx lithographica (Table 2) than other There are 13 dentary teeth, recurved and similar in size to known theropods. The holotype is roughly twice the size of the maxillary teeth with crowns nearly 7 mm in length. the Berlin Archaeopteryx (De Beer, 1954), but the head is The dentary teeth have 5 posterior denticles per millime- two and one half times as large (12 cm vs. 4.8 cm). ter. Anterior denticles are not easily discernable. The coro- The skull of the holotype is virtually complete (Fig. 1). noid process is low and includes a delicate coronoid bone. It is lightly built with a narrow snout and large, dorsally The external surface of each dentary has many small fo- inflated braincase. Additionally, the skull has large upper ramina, especially abundant on the anterior portion. A temporal openings, T-shaped lacrimal, long narrow frontals mandibular fenestra is present and heavily built. Unfused with pronounced orbital rim, large antorbital fenestrae, articulars are present. maxilla with 2 accessory fenestrae, and 9 sharply recurved The vertebral column consists of 22 presacral vertebrae, teeth up to 6 mm in length. There are 4.3 denticles per including 9 cervicals, a cervicodorsal, and 13 dorsal verte- millimeter, but anterior denticles are visible on only a few brae. Large pleurocoels occur on the cervical and dorsal teeth. They are more closely spaced (6.0 to 6.5 per milli- vertebrae. Posterior cervicals, cervicodorsal, and the ante- meter) and smaller. The premaxilla contains 4 alveoli, but rior dorsal vertebrae centra bear a ventral keel, similar to the tooth crowns are broken and mostly missing. Jugals are Deinonychus. There are 5 fused sacral and 23 preserved long and parallel sided with a row of small, ventrally posi- caudal vertebrae. The posterior end of the caudal series is tioned foramina along the ventral margin. The ascending missing. Elongated zygopophyseal rods and extensions of process of the jugal is inclined posteriorly at nearly 45 the chevrons overlap forward, producing the bony tail degrees. typical of dromaeosaurid dinosaurs. Burnham et al.—Remarkable New Birdlike Dinosaur (Theropoda: Maniraptora) 3 parietal Figure 1. Bambiraplor feinbergi n. gen. and n. sp., holotype (FIP 001); I, skull and mandibular elements in left lateral view; 2, restored skull in left lateral view; 3, restored skull in dorsal view. Scale bar: 5 cm (new). Most ribs and gastralia are damaged. No single rib or restoration, the shape of the ribcage must remain conjec- gastralium preserves its full length, although the volume of tural. rib heads and fragments suggests that the ribcage and The proximal caudal vertebrae and rod-stiffened por- gastral basket were originally complete. Pending further tion of the tail have a distinctly upward curve (Fig. 2). It is 4 The University of Kansas Paleontological Contributions The forelimbs are essentially as in Deinonychus antirrhopus (Ostrom, 1969b), although they are proportionally longer (Table 2). The wrist contains at least two elements, includ- ing a semilunate and a carpal with two saddle-shaped fac- ets and a concave distal face. At least one other small element may also be a carpal.
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