Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan and the phylogenetic position of Itemirus medullaris Kurzanov, 1976

Abstract

Skeletal remains of dromaeosaurid theropods are uncommon in the richly fossiliferous continental strata of the Upper Cretaceous (Turonian) Bissekty Formation of the Kyzylkum Desert in Uzbekistan. The phylogenetic position of the first published specimen, a partial braincase designated as the holotype of Itemirus medullaris Kurzanov, 1976, has long been contentious. Our examination of the specimen supports its attribution to Dromaeosauridae. Additional, mostly well-preserved dromaeosaurid skeletal remains from the Bissekty Formation include cranial bones, teeth, vertebrae, and some podial elements. They are tentatively referred to the same taxon, Itemirus medullaris, and establish the presence of dromaeosaurid paravians in present-day Central Asia during the Turonian.

Full text

Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty
Formation (Upper Cretaceous: Turonian) of Uzbekistan and
the phylogenetic position of Itemirus medullaris Kurzanov, 1976
Hans-Dieter Sues
a
,
*
, Alexander Averianov
b
,
c
a
Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, MRC 121, PO Box 37012, Washington, DC 20013-7012, USA
b
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, Saint Petersburg 199034, Russia
c
Department of Sedimentary Geology, Geological Faculty, Saint Petersburg State University, 16 liniya VO 29, 199178 Saint Petersburg, Russia
article info
Article history:
Received 14 March 2014
Accepted in revised form 18 June 2014
Available online
Keywords:
Dinosauria
Theropoda
Paraves
Dromaeosauridae
Cretaceous
Uzbekistan
abstract
Skeletal remains of dromaeosaurid theropods are uncommon in the richly fossiliferous continental strata
of the Upper Cretaceous (Turonian) Bissekty Formation of the Kyzylkum Desert in Uzbekistan. The
phylogenetic position of the first published specimen, a partial braincase designated as the holotype of
Itemirus medullaris Kurzanov, 1976, has long been contentious. Our examination of the specimen sup-
ports its attribution to Dromaeosauridae. Additional, mostly well-preserved dromaeosaurid skeletal
remains from the Bissekty Formation include cranial bones, teeth, vertebrae, and some podial elements.
They are tentatively referred to the same taxon, Itemirus medullaris, and establish the presence of dro-
maeosaurid paravians in present-day Central Asia during the Turonian.
Published by Elsevier Ltd.
1. Introduction
The continental strata of the Turonian-age Bissekty Formation in
the Kyzylkum Desert in Uzbekistan have yielded a very diverse
assemblage of vertebrates including dinosaurs. This assemblage is of
particular interest among known occurrences of Late Cretaceous
tetrapods in Central Asia for being stratigraphically well constrained
and for documenting a lowland, coastal plain setting. Previously, we
reported on the hadrosauroid Levnesovia transoxiana, the stem
ceratopsid Turanoceratops tardabilis, the troodontid Urbacodon sp.,
and skeletal remains of indeterminate tyrannosauroids (Averianov
and Sues, 2007, 2012b; Sues and Averianov, 2009a,b). In addition,
we reviewed the stratigraphic correlation of the Cretaceous as-
semblages of continental vertebrates from the Kyzylkum Desert
with those from the Gobi Desert (Averianov and Sues, 2012a).
The skeletal remains of dromaeosaurid theropods described in
the present paper were collected from strata of the Bissekty For-
mation exposed along an approximately 8 km long escarpment
near the small settlement of Dzharakuduk (variously given in the
literature as Dzhara-Kuduk, Dzhirakuduk, Dzhyrakuduk, Bissekty,
and Kul'beke) in the central Kyzylkum Desert, 32 km SW of Myn-
bulak in the Navoi district, Uzbekistan (Nessov, 1995, 1997;
Archibald et al., 1998;Fig. 1A-B). The escarpment extends from
about 42

06
0
22.60
00
N and 62

37
0
09.00
00
Eto42

05
0
44.22
00
N and
62

41
0
06.49
00
E. The Bissekty Formation comprises an up to about
80 m thick succession of medium-grained, poorly lithified, cross-
bedded fluvial sandstones and clast-supported, well-cemented
infraformational conglomerates (Fig. 1C). Most of the vertebrate
remains are disassociated.
Dromaeosaurids were first identified from the Kyzylkum Desert
based on material from the most fossiliferous locality complex,
Dzharakuduk, where exposures of middle to upper Turonian strata
of the Bissekty Formation have yielded a diverse assemblage of
continental vertebrates. They have long been cited in faunal lists for
this assemblage (Martinson et al., 1986; Nessov, 1988, 1992), but
there has never been any documentation of the actual remains.
Even Nessov's (1995) survey of dinosaurs from the territories of the
former USSR does not provide further details regarding the dro-
maeosaurid fossils. Nessov (1995, pl. 2, fig. 11) illustrated a tooth
from Dzharakuduk and referred it to Dromaeosauridae. He also
assigned to indeterminate “Segnosauria”(¼Therizinosauroidea)
and Theropoda various isolated bones that we reassign here to
Dromaeosauridae (see below). Finally, Nessov (1995, pl. 2, fig. 17)
figured a braincase fragment that he referred to a possibly
*Corresponding author.
E-mail addresses: suesh@si.edu (H.-D. Sues), dzharakuduk@mail.ru
(A. Averianov).
Contents lists available at ScienceDirect
Cretaceous Research
journal homepage: www.elsevier.com/locate/CretRes
http://dx.doi.org/10.1016/j.cretres.2014.06.007
0195-6671/Published by Elsevier Ltd.
Cretaceous Research 51 (2014) 225e240

dromaeosaurid theropod (CCMGE 466/12457). This specimen has
since been reidentified as troodontid (Averianov and Sues, 2007)
and will be described elsewhere.
Kurzanov (1976) provided a detailed description of an excel-
lently preserved partial braincase of a small theropod dinosaur
(PIN 327/699), which Anatoly K. Rozhdestvensky had collected at
Dzharakuduk in 1958. He designated it as the holotype of a new
taxon Itemirus medullaris. Kurzanov was unaware that Rozhdest-
vensky had confused the locality complex at Dzharakuduk with
that of neighboring Itemir (Rozhdestvensky, 1964;Fig. 1B) and thus
mistakenly based the generic name on the latter location.
The phylogenetic position of Itemirus medullaris has remained
contentious since its original description. Kurzanov (1976) placed
this taxon in a monotypic family Itemiridae, which he considered
related to both Tyrannosauridae and Dromaeosauridae but more
closely to the latter. In the first edition of the reference work The
Dinosauria,Molnar (1990) classified Itemirus medullaris as a prob-
lematic “carnosaur,”whereas, in the second edition of this book,
Holtz (2004) referred it without further explanation to Tyranno-
sauroidea. In an abstract, Miyashita (2011) considered Itemirus a
basal tyrannosauroid but did not present compelling evidence in
support of his hypothesis. Currie (2000, p. 450) observed that the
braincase of Itemirus medullaris is “much closer in all but one respect
(the laterally excavated basipterygoid process) to a dromaeosaurid
braincase.”Since that time Burnham (2004) has documented the
presence of laterally excavated basipterygoid processes in the (ju-
venile) holotype of the dromaeosaurid Bambiraptor feinbergorum.
Averianov and Sues (2004) referred Itemirus to Dromaeosauridae.
The only phylogenetic analysis published to date that included
Itemirus medullaris as a terminal taxon recovered it as a velocir-
aptorine dromaeosaurid, specifically as the sister-taxon to Veloci-
raptor (Longrich and Currie, 2009). The synoptic review of
dromaeosaurid diversity and phylogeny by Turner et al. (2012) does
not discuss Itemirus. However, inclusion of Itemirus medullaris in the
extensive character-taxon matrix compiled by those authors con-
firms its referral to Dromaeosauridae (see below). In a recent review
of dinosaurs from Russia and neighboring countries, Alifanov (2012)
also referred Itemirus to Dromaeosauridae.
Dromaeosaurid remains are among the least common theropod
fossils from the Upper Cretaceous of Kyzylkum Desert. So far teeth
of these theropods have been identified only from the middle to
upper Turonian Bissekty Formation at the localities Dzharakuduk II,
Uchkuduk II, and Zengekurgon 3. Bones referable to this group are
known only from Dzharakuduk II. Although the limited available
material shows a considerable size range there are no morpho-
logical differences among the few comparable remains that would
clearly establish the presence of more than one dromaeosaurid
taxon in the theropod assemblage from Dzharakuduk. Thus, we
tentatively assign all known remains to Itemirus medullaris.
Institutional abbreviations. CCMGE eChernyshev's Central
Museum of Geological Exploration, Saint Petersburg, Russia; PIN e
Borissiak Paleontological Institute, Russian Academy of Sciences,
Moscow, Russia; ZIN PH ePaleoherpetological Collection, Zoolog-
ical Institute, Russian Academy of Sciences, Saint Petersburg, Russia.
Locality abbreviations. The locality information following catalog
numbers used prefixes established by Nessov for localities within
Fig. 1. Geographic setting and stratigraphic section for the Dzharakuduk locality complex, Uzbekistan. A, outline map of Uzbekistan and neighboring countries with the position of
the Itemir-Dzharakuduk depression marked by a star. B, sketch map of the Itemir-Dzharakuduk escarpments (D). Abbreviations: 1, Itemir well; 2, Dzharakuduk wells; 3, Kul'beke
well; 4, Bissekty well; 5, Khodzhakhmet well. C, stratigraphic section of the Bissekty Formation. The arrow in C denotes the position of the site CBI-14, a particularly productive
locality for microvertebrate remains including dromaeosaurid teeth in a channel deposit.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240226

the middle-upper and lower parts of the Bissekty Formation,
respectively: CBI eCentral (Kyzylkum) Bissekty; CDZH eCentral
(Kyzylkum) Dzharakuduk.
Measurements. Metapodials and phalanges: DW - maximum
width of distal end. All measurements are in millimeters.
2. Systematic paleontology
Dinosauria Owen, 1842
Saurischia Seeley, 1887
Theropoda Marsh, 1881
Maniraptora Gauthier, 1986
Paraves Sereno, 1997
Dromaeosauridae Matthew and Brown, 1922 sensu Turner et al.,
2012
Dromaeosaurinae Matthew and Brown, 1922 sensu Turner et al.,
2012
Itemirus Kurzanov, 1976
Itemirus medullaris Kurzanov, 1976
1976 Itemirus medullaris: Kurzanov, p. 129, figs. 1-3
1987 Itemirus medullaris: Kurzanov, fig. 37
1995 Segnosauria indet. [partim]: Nessov, p. 36, pl. 2, fig. 5
1995 Alectrosaurus sp. [partim]: Nessov, p. 38
1995 Dromaeosauridae [indet.]: Nessov, pl. 2, fig. 11
1995 Theropoda [indet.]: Nessov, pl. 1, fig. 4
1997 Theropoda [indet.]: Nessov, pl. 20, fig. 19.
Holotype. PIN 327/699, incomplete posterior portion of a braincase,
cut sagittally during preparation and with the partial right side
further dissected (Fig. 4).
Type locality and stratigraphic horizon. Dzharakuduk II (not Itemir,
contra Kurzanov, 1976), Central Kyzylkum Desert, Uzbekistan. Bis-
sekty Formation; age: Late Cretaceous, middle to late Turonian.
Referred material used in this study. ZIN PH 967/16, left frontal
(Fig. 2); CCMGE 600/12457 and ZIN PH 357/16, partial maxillae
(Fig. 3); ZIN PH 2338/16, anterior portion of dentary (Fig. 4);
numerous isolated teeth (of which ZIN PH 2352/16, ZIN PH 2353/16,
and ZIN PH 2351/16 are illustrated in Fig. 6); ZIN PH 89/16, ZIN PH
92/16 (Fig. 7), ZIN PH 90/16 (Fig. 8) and ZIN PH 2263/16, cervical
vertebrae; ZIN PH 13/16 (Fig. 9), ZIN PH 73/16 (Fig. 10F-K), ZIN PH
74/16, ZIN PH 75/16, ZIN PH 96/16, ZIN PH 2269/16 (Fig. 10A-E), and
Fig. 2. ZIN PH 967/16 (CBI, 2004), left frontal referred to Itemirus medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, ventral view; B, lateral view; C,
dorsal view; D, medial view; E, posterior view. Abbreviations: alp, anterolateral process; amp, anteromedial process; crc, crista cranii; ich, impression of cerebral hemisphere; iob,
impression of olfactory bulb; nf, nasal facet; om, orbital margin; pop, postorbital process; stf, supratemporal fossa. Scale bar equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 227

CCMGE 456/12457, dorsal vertebrae; ZIN PH 2273/16 (Fig. 10F-K),
ZIN PH 2346/16 (Fig. 11), caudal vertebrae; ZIN PH 182/16 (Fig. 12)
and ZIN PH 183/16, metacarpals I; ZIN PH 11/16, pedal phalanx II-2
(Fig. 13); ZIN PH 12/16, pedal phalanx III-4.
Diagnosis. None of the features in the original diagnosis offered by
Kurzanov (1976) has diagnostic value, and two characters cited by
this author (position of foramen for endolymphatic duct and pres-
ence of “recessus interacusticus”) are based on incorrect anatomical
interpretations. Itemirus is referable to Dromaeosauridae based on
the following synapomorphies for this clade hypothesized by
Turner et al. (2012): 17(0), accessory tympanic recess dorsal to crista
interfenestralis absent; 96(0), anterior cervical centra level with or
shorter than posterior extent of neural arch; 103(1), parapophyses
of posterior trunk vertebrae distinctly projected on pedicels. Within
Dromaeosauridae Itemirus medullaris is referable to Dromaeosaur-
inae on the basis of the following synapomorphies: 91(1), pre-
maxillary tooth crowns asymmetrical (D-shaped) in cross-section,
with flat lingual surface; 238(1), jugal process of maxilla ventral to
external antorbital fenestra dorsoventrally wide. Among Dro-
maeosaurinae, Itemirus medullaris differs from Dromaeosaurus
albertensis in characters 15(1), basipterygoid recesses on dorsolat-
eral surfaces of basipterygoid processes present; 247(1), anterior
denticles of teeth significantly smaller than posterior denticles.
Itemirus differs from Utahraptor ostrommaysorum in character
265(1), pleurocoels present in anterior dorsals. Itemirus medullaris
differs from both Utahraptor ostrommaysorum and Achillobator
giganticus in character 318(1), lateral surfaces of centra of thoracic
vertebrae have deep, emarginated fossae.
3. Description
3.1. Skull
3.1.1. Frontal
An exquisitely preserved left frontal of a juvenile individual
(ZIN PH 967/16; Fig. 2) closely resembles the frontals of other
dromaeosaurids (Currie, 1987). It is triangular and twice as long as
wide. The anterior end of the frontal has two pointed processes that
are separated by a slot, possibly for the reception of the lacrimal
(Currie, 1987, 1995). The large anteromedial process also bears a
dorsally extensive articular facet for the medial prong of the nasal.
The smaller, tapered anterolateral process is completely covered
dorsally by a facet for the lateral prong of the nasal or for the
lacrimal. The orbital margin of the frontal forms is sharp and rather
short. It is delimited by the anterolateral process anteriorly and by a
short but distinct posterolateral postorbital process posteriorly. The
postorbital process of the frontal contacted the postorbital along a
narrow ventral facet. The supratemporal fossa is demarcated by a
distinct but weak circular line extending from the tip of the post-
orbital process toward the posteromedial corner of the frontal. The
bone slants posterolaterally in the supratemporal fossa, where
there is a deep pit posteromedial to the posterolaterally situated
postorbital process. The medial edge of the frontal is straight and of
even thickness except near the anterior end, forming an interdigi-
tating sutural surface for the opposing frontal along its entire
length. The interorbital width of the frontals was rather narrow.
The dorsal surface of the frontal is depressed in the anterior half
and domed posteriorly above the cerebral hemisphere. The dome of
one frontal was confluent with that of its antimere. On the ventral
side of the bone, the deep ventral impression for the cerebral
hemisphere is only slightly larger than the shallower anteroventral
impression for the olfactory bulb. The arcuate crista cranii divides
the ventral surface of the frontal into nearly equal parts, laterally
forming the roof of the orbit. The sutural contact with the parietal is
interdigitating medially.
3.1.2. Maxilla
We tentatively assign the posterior portion of a left maxilla
(CCMGE 600/12457; Fig. 3A-C) to Dromaeosauridae rather than
Tyrannosauroidea (Nessov, 1995, p. 38) based on the long posterior
ramus behind the tooth row and the absence of distinct interdental
plates. The posterior portions of two undisputed tyrannosauroid
maxillae from Dzharakuduk (ZIN PH 2/16 and ZIN PH 676/16;
Averianov and Sues, 2012b) differ in both features. CCMGE 600/
12457, which is about 150mm long, preserves the last four alveoli as
well as parts of two preceding ones. The specimen appears to have
Fig. 3. Fragments of maxillae referred to Itemirus medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A-C, CCMGE 600/12457 (CBI-15, 1980), posterior
portion of left maxilla. A, lateral view; B, ventral view; C, medial view. D-F, ZIN PH 357/16 (CBI-5a, 1989), posterior fragment of right maxilla. D, medial view; E, ventral view; F,
lateral view. Scale bars each equal 3 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240228

Fig. 4. PIN 327/699, braincase ofItemirus medullaris (holotype) fromthe Bissekty Formation (Turonian)at Dzharakuduk,Uzbekistan. A, lateral view of left half;B, medial view of lefthalf; C,
occipital view. Abbreviations: bpp, basipterygoid process; br, basisphenoid recess; bt, basal tuber; ds, dorsum sellae; dtr, dorsal tympanic recess; fm, foramen magnum; fr, floccular recess;
mf, metotic foramen; oc, occipital condyle; otr, otic recess; pn, pneumatic recess on basipterygoid process; ptr, posterior tympanic recess; pvf, posterior exit of middle cerebral vein; scr,
subcondylar recess; vcm, groove for middlecerebral vein; vs, foramen for venous sinus. Roman numerals denote foramina for passage of cranial nerves. Scale barequals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 229

been damaged since Nessov examined it because he cited a higher
number of preserved alveoli. The more complete of the two partial
alveoli (fifth alveoluscounting forwards from the posterior end of the
tooth row) preserves a fragment of a tooth as well as an impressionof
the finely serrated mesial carina of that tooth in ironstone. The four
alveoli decrease in size fromthe first to the last. The posterior portion
of the maxilla is transversely narrow and slightly deflected laterally.
A deep groove, probably for the reception of the anterior process of
the jugal, extends along mostof the dorsal margin. At the level of and
medial to the anterior end of this groove, a canal penetrates the
dorsal surface of the bone, leading tothe sixth alveolus. Little detail is
evident on the poorly preserved lateral surface of the maxilla. Its
medial surface does not show distinct interdental plates. A narrow
lingual groove for the dental lamina extends above the alveoli,
turning toward the alveolar margin and terminating at the posterior
end of the last alveolus. It contains foramina, which areclearly visible
above each of the last two alveoli. The medially directed palatal shelf
of the maxilla has been largely lost due to postmortem breakage.
The structurally similar but larger fragment of a right maxilla
ZIN PH 357/16 (Fig. 3D-F) preserves four posterior alveoli (the
anteriormost of which is incomplete). The combined length of three
posterior alveoli is 48.5 mm (compared to 33 mm in CCMGE 600/
12457). The posterior portion of the bone is also slightly deflected
laterally. It bears the same deep groove along its dorsal edge also
present in CCMGE 600/12457, but the groove terminates anteriorly
near a large opening leading to the fourth alveolus from the back
(sixth in CCMGE 600/12457).
3.1.3. Braincase
The holotype of Itemirus medullaris, PIN 327/699, is an incom-
plete but excellently preserved posterior portion of a braincase
(Fig. 4). It was cut with a saw along the sagittal plane during
preparation; additional smaller cuts were made on the less com-
plete right wall of the braincase. Most of the paroccipital processes
were broken off prior to discovery of the specimen. The individual
bones of the braincase are almost indistinguishably fused to each
other. Kurzanov (1976) described the specimen in detail, obviating
the need for a full anatomical account here.
The occiput is only slightly inclined anterodorsally relative to
the basioccipital floor of the endocranial cavity. The foramen
magnum is drop-shaped with the pointed ventral end. The supra-
occipital bears an indistinct median (nuchal) ridge bordered on
either side by a slightly concave surface. Dorsolateral to the foramen
magnum, apparently on the border between the supraoccipital
and otoccipital, there is a posterior opening forpassage of the middle
cerebral vein (Fig. 4A, C). The position of this opening is similar to
that in Dromaeosaurus and Velociraptor (Currie, 1995; Norell et al.,
2004), whereas in Deinonychus these foramina are situated closer
Fig. 5. ZIN PH 2338/16 (CBI-14, 1998), fragment of right dentary referred to Itemirus
medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A,
dorsal view; B, medial view; C, lateral view. Abbreviation: mg, Meckelian groove. Scale
bar equals 1 cm.
Fig. 6. Isolated tooth crowns referred to Itemirus medullaris from the Bissekty For-
mation (Turonian) at Dzharakuduk, Uzbekistan. A-C, ZIN PH 2352/16 (CBI-14, 1984). A,
labial view; B, mesial view; C, lingual view. D-F, ZIN PH 2353/16 (CBI-14, 1991). D,
lingual view; E, mesial view; F, labial view. G-I, ZIN PH 2351/16 (1988). G, lingual view;
H, mesial view; I, labial view. Scale bar equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240230

to the midline and issue laterally directed grooves (Brinkman et al.,
1998). The otoccipital surface around the foramen magnum is ver-
tical, as in other dromaeosaurids except Bambiraptor,where it slopes
anterodorsally.
The occipital condyle is only slightly less wide than the foramen
magnum. It is almost round in posterior view, as in Deinonychus
(Brinkman et al., 1998), unlike the crescent-shaped occipital
condyle in Velociraptor (Norell et al., 2004). Lateral to the occipital
condyle near the inferred suture between the otoccipital and
basioccipital, there is a large shallow depression, which contains
openings for the vagus (X), accessory (XI), and hypoglossal (XII)
nerves. A similar but more distinct, bowl-like depression is present
in Velociraptor and Deinonychus but not in either Dromaeosaurus or
Bambiraptor (Norell et al., 2004; Turner et al., 2012).
The basioccipital tubera are short and diverge ventrolaterally
from the midline (Fig. 4C), as in Velociraptor and Bambiraptor (Norell
et al., 2004), whereas the tubera are much shorter and extend almost
parallel in Dromaeosaurus (Currie, 1995). On the posterior side of
either basioccipital tuber, ventral to the depression with openings
for cranial nerves, a groove extends along the tuber.Kurzanov (1976)
considered this feature the site of insertion for m. rectus capitis
anterior. A similar groove is present also in Velociraptor (Norell et al.,
2004) and has been interpreted as a subcondylar pneumatic recess
by Witmer (1997). On the ventral side of the basioccipital, a deep
recess extends between the basal tubera, similar to the condition in
Dromaeosaurus but unlike in Velociraptor (Fig. 4B).
The basipterygoid processes of the basisphenoid diverge ven-
trolaterally from the sagittal midline at approximately the same
angle as the basal tubera (Fig. 4C). They are long and project
ventrally beyond the level of the basal tubera, as in Velociraptor
(Norell et al., 2004). Unlike in the latter taxon, the basipterygoid
processes do not turn laterally at their distal ends.
On the left side of the braincase, a stout, vertical metotic strut
extends between the basioccipital tuber and the base of the broken
paroccipital process (Fig. 4A). This strut separates the depression
with the exits of the posterior cranial nerves on the posterior side
from the metotic opening on the lateral side, containing the exits of
cranial nerves IX-XII and the internal jugular vein. Dorsal to the
metotic strut, breakage of the paroccipital process reveals a pneu-
matic space, the posterior tympanic recess (Fig. 4A). A slender crista
interfenestralis separates the metotic foramen from the fenestra
ovalis (Fig. 4A). Both openings are contained in a shallow otic
recess. More anteriorly, there is a larger opening for passage of the
facial nerve (VII; Fig. 4A) and, behind it, the otic recess. A large
foramen for the trigeminal nerve (V) is located anterodorsal to the
foramen for the facial nerve (Fig. 4A), as in Velociraptor (Norell et al.,
2004), whereas in Dromaeosaurus it is situated anterior to that
opening (Currie, 1995). As in the latter taxon but unlike in Veloci-
raptor, there is no prootic recess ventral to the foramen for the facial
nerve. There is no otosphenoidal crest, unlike in Dromaeosaurus
(Currie, 1995). Some distance ventral to the foramen for the facial
nerve, there is the posterior entrance for the canal carrying the
internal carotid artery at the base of the basipterygoid process.
Dorsal and slightly posterior to the trigeminal foramen there is a
large and shallow dorsal tympanic recess (Fig. 4A). It extends onto
the (mostly broken) paroccipital process posterolaterally. Unlike in
Fig. 7. ZIN PH 92/16 (CDZH-17a), anterior cervical vertebra referred to Itemirus medullaris from Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, dorsal view; B, ventral
view; C, anterior view; D, lateral view; E, posterior view. Abbreviations: ep, epipophysis; p, pneumatopore; pa, parapophysis; poz, postzygapophysis; prz, prezygapophysis. Scale bar
equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 231

Velociraptor (Norell et al., 2004), the dorsal tympanic recess lacks a
pneumatic opening.
On the medial side of the braincase, near the incomplete ante-
rior margin, there is a large opening for the trigeminal nerve
(V; Fig. 4B) and, ventral to it, a small foramen for the abducens
nerve (VI). Posterior to the trigeminal opening, the foramen for the
facial nerve (VII) is surrounded by exits for the cochlear and
vestibular branches of the vestibulocochlear nerve (VIII; Fig. 4B).
The arrangement of these foramina is the same as in Dromaeo-
saurus (Currie, 1995)orVelociraptor (Norell et al., 2004). Posterior
and somewhat ventral to these openings the large, cleft-like
metotic foramen transmitted cranial nerves IX-XI (Fig. 4B). More
posteriorly, two small openings represented passages for branches
of the hypoglossal nerve (XII).
The large and deep floccular recess (misidentified by Kurzanov
as a “recessus interacusticus”) is situated in the middle of the
medial surface of the braincase above the openings for the cranial
nerves (Fig. 4B). Posteriorly, the recess is bounded by the bony
swelling around the semicircular canals. At the dorsal end of this
inflated ridge, there is a short sulcus terminating in a posterior
foramen for passage of the middle cerebral vein (Fig. 4B). Kurzanov
(1976) incorrectly interpreted the opening for a venous sinus close
to the lateral margin of the foramen magnum and posterior to the
floccular recess as the foramen for the endolymphatic duct (Fig. 4B).
Norell et al. (2004) correctly identified the foramen for the endo-
lymphatic duct in Velociraptor as being situated between the floc-
cular recess and the metotic foramen.
3.1.4. Dentary
We refer a fragment of the anterior portion of a right dentary
(ZIN PH 2338/16; Fig. 5) to Dromaeosauridae based on the absence
of distinct interdental plates. The anterior end of the fragment is
distinctly higher than the posterior end and slightly turned medi-
ally towards the symphysis. There are seven alveoli, all more or less
equal in size. They are somewhat compressed mediolaterally and
closely spaced. On the lingual side of the jaw, the Meckelian groove
is deep posteriorly. At the anterior end of the fragment, just below
the Meckelian groove, a small oval foramen opens into the inferior
Fig. 8. ZIN PH 90/16 (CBI-14, 1989), posterior cervical vertebra referred to Itemirus medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, dorsal view; B,
ventral view; C, posterior view; D, lateral view; E, anterior view. Abbreviations: di, diapophysis; p, pneumatopore; pa, parapophysis; poz, postzygapophysis. Scale bar equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240232

alveolar canal. The labial (lateral) side of dentary bears two longi-
tudinal rows of neurovascular foramina, each of which becomes a
groove posteriorly.
3.1.5. Teeth
There are numerous isolated teeth with labiolingually flattened,
recurved crowns that show variation in the size and density of
serrations along the mesial and distal carinae (Fig. 6). Teeth from
anterior positions in the jaws show the characteristic lingual
displacement of the mesial carina. Dromaeosaurid teeth cannot
always be unambiguously distinguished from those of juvenile
tyrannosauroids, but we assume that the stouter tooth crowns from
Dzharakuduk belong to Tyrannosauroidea. The distal carinae on the
dromaeosaurid teeth bear between 3 and 6 subrectangular denti-
cles per 1 mm of cutting edge. The crown of ZIN PH 2344/16 is
triangular in transverse section and separated from the root by a
slight constriction; this tooth appears to be from the premaxilla.
Some of the crowns show distinct wear.
3.2. Vertebral column
3.2.1. Cervical vertebrae
Most of the dromaeosaurid cervicals from Dzharakuduk have
long, in lateral view parallelogram-shaped to triangular centra
with the anterior articular surface facing almost ventrally. They
closely resemble the possibly fourth through seventh cervical
vertebrae in Deinonychus (Ostrom, 1969,figs. 29-30). Two other
cervicals have relatively shorter, more rectangular centra, and
their anterior articular surfaces face somewhat more vertical. They
probably represent posterior cervicals, perhaps the eighth or ninth
(which were not identified by Ostrom (1969) for Deinonychus). The
more anterior cervicals closely resemble the postaxial cervical
vertebrae of Deinonychus (Ostrom, 1969). The centra show pro-
nounced angling, with steeply anteroventrally facing, transversely
concave, and kidney-shaped anterior articular surfaces. They are
widest across the ventrolaterally situated parapophyses anteriorly
and are moderately constricted at mid-length. On either side of
the centrum, there is a deep, oval pleurocoel behind the para-
pophysis. The distinct pre- and postzygapophyses extend beyond
the respective ends of the centra. Their large articular facets are
convex on the prezygapophyses and concave on the post-
zygapophyses, respectively, and placed lateral to but level with the
neural canal. More anterior cervicals (e.g., ZIN PH 89/16 and 92/16;
Fig. 7) have large, wing-like epipophyses, which surmount the
postzygapophyses and overhang them posteriorly. On the more
posterior cervicals (ZIN PH 90/16 and 2263/16; Fig. 8), the epi-
pophyses are much smaller and low. The neural spines are rather
low dorsoventrally and short anteroposteriorly. Deep triangular
recesses for attachment of interspinous ligaments excavate their
bases anteriorly and posteriorly.
3.2.2. Dorsal vertebrae
One nearly complete dorsal (ZIN PH 13/16; Fig. 9) and four
incomplete ones closely resemble the ‘cervico-dorsal’vertebra
Fig. 9. ZIN PH 13/16 (CBI-14, 1980), first dorsal vertebra referred to Itemirus medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, dorsal view; B,
ventral view; C, anterior view; D, lateral view; E, posterior view. Abbreviations: di, diapophysis; ep, epipophysis; hy, hypapophysis; p, pneumatopore; pa, parapophysis; poz,
postzygapophysis; prz, prezygapophysis. Scale bar equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 233

Fig. 10. Posterior dorsal vertebrae referred to Itemirus medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A-E, ZIN PH 2269/16 (CBI-14, 1984). A, ventral
view; B, dorsal view; C, posterior view; D, right lateral view; E, anterior view. F-K, ZIN PH 2273/16 (CBI-5a, 1980). F, dorsal view; G, ventral view; H, anterior view; I, left lateral view;
K, posterior view. Abbreviations: di, diapophysis; hp, hyposphene; idf, infradiapophyseal fossa; ipf, infrapostzygapophyseal fossa; irf, infraprezygapophyseal fossa; ns, neural spine;
p, pneumatopore; pa, parapophysis; prz, prezygapophysis. Scale bars each equal 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240234

identified by Ostrom (1969, fig. 32) in Deinonychus. The neural
spines and transverse processes were broken off. The large zyg-
apophyseal facets are widely spaced and only slightly inclined.
Posterior and slightly lateral to the prezygapophyseal facet, a large
pneumatic recess opens into the neural arch. The epipophyses are
large but do not overhang the postzygapophyses posteriorly. The
large concave parapophyseal facets are placed on the anterior rim
of the centrum. The centrum is short, not angled, and bears a
prominent median ventral keel, which forms a hypapophysis
(damaged in ZIN PH 13/16 but complete in ZIN PH 96/16). A large
pleurocoel is present on either side posteroventral to the para-
pophysis, and a smaller one opens at the base of the hypapophysis
below the pleurocoel (or several small openings between the
pleurocoels and the parapophysis in ZIN PH 96/16).
The dorsal centra ZIN PH 74/16 and CCMGE 456/12457
(Nessov,1995, pl. 2, fig. 5) lack a hypapophysis but have an anterior
articular surface that extends distinctly more ventrally than the
posterior one. ZIN PH 74/16 also has a reduced pleurocoel and
parapophyses; the latter are placed above the neurocentral suture.
These vertebrae are probably anterior dorsals posterior to the first
dorsal.
Several vertebrae (e.g., ZIN PH 75/16 and ZIN PH 2269/16;
Fig. 10A-E) represent posterior dorsals. Their centra are shorter
than high, slightly amphicoelous, and lack mid-ventral keels. The
anterior and posterior articular surfaces of the centra either extend
parallel to each other or slightly converge ventrally. The pleurocoel
is deep, oval, and situated below the neurocentral suture. The
parapophysis is much smaller than that on the first dorsal and
Fig. 11. ZIN PH 2346/16, posterior caudal vertebra referred to Itemirus medullaris from
the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, anterior view; B,
dorsal view; C, lateral view; D, posterior view; E, ventral views. Abbreviation: prz,
prezygapophysis. Scale bar equals 5 mm.
Fig. 12. ZIN PH 182/16 (CBI-14, 1980), left metacarpal I referred to Itemirus medullaris
from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A, proximal view;
B, distal view; C, medial view; D, anterior view; E, lateral view; F, posterior view. Scale
bar equals 1 cm.
Fig. 13. ZIN PH 11/16 (CDZH-14a, 1980), pedal phalanx II-2 referred to Itemirus
medullaris from the Bissekty Formation (Turonian) at Dzharakuduk, Uzbekistan. A,
dorsal view; B, lateral view; C, ventral view. Scale bar equals 1 cm.
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 235

placed on the pedicle of the neural arch. On the lateral side of the
neural arch, two distinct vertical struts converge dorsally from the
parapophysis and the posterior margin of the neural arch towards
the base of the transverse process. These struts delimit deep
infraprezygapophyseal, infradiapophyseal, and infrapostzygapo-
physeal fossae. Among these fossae, the infradiapophyseal one is
the deepest, with the pneumatopore at its bottom opening into an
internal cavity of the neural arch. Compared with the first dorsal,
the prezygapophyses on the posterior dorsals are much smaller,
more closely spaced, and face more medially. The neural spine is
short anteroposteriorly on some vertebrae (e.g., ZIN PH 2269/16,
Fig. 10B) but distinctly longer in others, which are possibly placed
further posteriorly along the dorsal column (e.g., ZIN PH 73/16;
Fig. 10F-K). The interspinous recesses are prominent and have the
ventral floor forming the floor of the hypantrum anteriorly and
continuing posteriorly into the hyposphene. The bars for attach-
ment of interspinous ligaments are moderately developed.
3.2.3. Caudal vertebrae
ZIN PH 2273/16 is an anterior caudal vertebra probably referable
to Dromaeosauridae. Except the lack of the parapophyses, it differs
from the posterior dorsals in that the box-like centrum is wider
than high and long and lacks pleurocoels. However, it still has a
depression on the lateral surface. There is no ventral groove nor are
there chevron facets, and this could be one of the anterior caudals.
Only a single (anterior) bony strut supports the transverse process,
and there are fossae on the lateral side of the neural arch. The
prezygapophyses are spaced similar to those on the posterior dor-
sals, but their facets are anteroposteriorly oriented (rather than
transverse as on posterior caudals). The anterior interspinous
recess has no ventral floor. The neural spine is short and confined to
the posterior part of the neural arch.
ZIN PH 2346/16 is a small, elongate posterior caudal (Fig. 11).
The ventral surface of its centrum is flattened except for trans-
versely concave areas at the anterior and posterior ends. The
(incompletely preserved) prezygapophyses are robust and appar-
ently projected anteriorly beyond the centrum. There are sharp
ridges along the dorsal surface of the prezygapophyses. The neural
arch is low and occupied the posterior two thirds of the neural
arch. It is flanked by lateral depressions for the reception of the
prezygapophyses of the succeeding vertebra. There is no neural
spine.
3.3. Manus
The first metacarpal (Fig. 12) is short and triangular in transverse
section. It is somewhat more elongated than the corresponding
bone in Deinonychus (Ostrom, 1969,fig. 62), but this feature is
exaggerated by the incomplete nature of the proximal end in ZIN
PH 182/16. The latter probably represents a juvenile specimen, and
adult individuals might have had a proportionately less elongate
metacarpal I. The lateral margin of the bone is straight. The concave
area for contact with metacarpal II occupies more than half of its
lateral surface. Distal to this area, the shaft of the metacarpal de-
viates slightly medially. On the ventral surface of the bone, just
distal to the proximal articular surface, a distinct pit marks the
insertion of m. flexor carpi radialis. The ventral surface is flat or
slightly concave whereas the dorsal surface is flat or convex. The
medial margin of the bone is sharp and proximodistally concave.
The distal articular end is ginglymoid and asymmetrical. Its lateral
condyle is much larger than the medial one and has a more pro-
nounced pit for the collateral ligament (shallow in the small bone
ZIN PH 182/16 and very deep in the largest element ZIN PH 183/16).
The greatest length of ZIN PH 182/16 is 39.0, and DW is 12.5 (ZIN PH
182/16) and 24.4 (ZIN PH 183/16), respectively.
3.4. Pes
The distinctive second phalanx of the second pedal digit, which
bears the large ungual, is represented by two elements from
Dzharakuduk, including one complete, large element (ZIN PH 11/
16; Fig. 13), on which the following account is based. This phalanx is
referable to Dromaeosauridae rather than to Troodontidae because
of a slight ‘neck’between the proximal and distal articular ends and
the pit for the collateral ligament is placed closer to the dorsal
margin (Colbert and Russell, 1969,fig. 15), whereas in Troodontidae
there is no ‘neck’and the pit for the collateral ligament occupies a
more central position (Russell, 1969,fig. 14). The proximal articular
facet forms a greatly enlarged ventral ‘heel,’which comprises more
than half of the total length of the bone, and is asymmetrically
divided by a distinct median ridge. Unlike in Deinonychus (Ostrom,
1969,fig. 75), the distal articular end is separated from the proximal
end only by a slight dorsoventral constriction; this difference may
be related to the much larger size of ZIN PH 11/16. The ginglymus
bears an articular facet with a curvature of about 180

, which ex-
tends much farther ventrally than dorsally. The condyles are
separated by a wide groove. Just below the dorsal terminus of the
ginglymus, the phalanx bears a deep pit for the collateral ligament
on either side. ZIN PH 11/16 has a greatest length of 96.4, more than
twice that of the corresponding phalanx in two specimens referred
to Deinonychus antirrhopus by Ostrom (1969, table 11).
One complete pedal ungual phalanx (ZIN PH 12/16) and several
incomplete ones are probably referable to Dromaeosauridae. These
slightly curved unguals have prominent ventral flexor tubercles
placed distal to the proximal articular facet. The complete element
resembles pedal ungual phalanx III-4 of Deinonychus (Ostrom, 1969,
fig. 75).
4. Phylogenetic position of Itemirus medullaris
To assess the phylogenetic position of Itemirus medullaris we
scored character states for this taxon into the comprehensive
character-taxon matrix compiled by Turner et al. (2012).We
created two additional terminal taxa: the first one included only
features from the holotypic braincase (PIN 327/699) and the second
one combined information from the holotype and the referred
specimens described above. The braincase has 14 characters that
could be scored into the data matrix (character numbers and
comparisons follow those in Turner et al. (2012)):
7(1): Crista interfenestralis distinctly depressed within the
middle ear opening. This derived character state is present in the
oviraptorid Citipati,Troodon, and all dromaeosaurids that can be
coded for this character.
8(0): Subotic recess (pneumatic fossa ventral to fenestra ovalis)
absent. It is plesiomorphically absent in most theropods and was ac-
quired independently among derived ornithomimids and troodontids.
9(0): Basisphenoid recess present between basisphenoid and
basioccipital. The same state is found in all dromaeosaurids coded
for this character.
10(0): Posterior opening of basisphenoid recess single. The
derived state, with a basisphenoid recess divided posteriorly into
two small, circular foramina, is occasionally present in theropods
such as Citipati, caenagnathids, Tyrannosaurus, and in all known
dromaeosaurids except Dromaeosaurus.
12(0): Basipterygoid processes projecting ventrally or ante-
roventrally. All dromaeosaurids coded for this character have the
plesiomorphic state.
13(0): Basipterygoid processes well developed, extending as a
distinct process from the base of the basisphenoid. The apomorphic
state, process abbreviated or absent, is present in oviraptorosaurs
and Erlikosaurus.
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14(0): Basipterygoid processes solid. A hollow basipterygoid
process is present in ornithomimosaurs, troodontids, and
caenagnathids.
15(1): Basipterygoid recesses on dorsolateral surfaces of basip-
terygoid processes present. This apomorphic state is present in all
dromaeosaurids coded except Dromaeosaurus.
16(0): Depression for pneumatic recess on prootic (dorsal
tympanic recess) absent. In most dromaeosaurids, the dorsal
tympanic recess is present as a deep, posterolaterally facing con-
cavity. The recess is also absent in Dromaeosaurus.
17(0): Accessory tympanic recess dorsal to crista interfenestralis
absent. It is absent in all dromaeosaurids coded for this character.
19(0): Exits of cranial nerves IXeXII flush with surface of exoc-
cipital. The plesiomorphic state is also found in Bambiraptor and
Dromaeosaurus.InVelociraptor and Tsaagan, the posterior exits for
these nerves are contained in a distinct, bowl-like depression.
54(1): Foramen magnum oval, taller than wide. Among Dro-
maeosauridae, this apomorphic state is also present in Tsaagan.In
Deinonychus and Velociraptor, the foramen magnum is subcircular,
slightly wider than high.
55(1): Occipital condyle subspherical, with constricted neck.
This apomorphic state is also present in Dromaeosaurus. In other
dromaeosaurids coded for this character, the occipital condyle lacks
a constricted neck.
225(0): Basal tubera set far apart, level with or beyond lateral
edge of occipital condyle and/or foramen magnum (may be con-
nected by a web of bone or separated by a large median notch). This
plesiomorphic state is found in most dromaeosaurids coded for this
character.
Adding the referred specimens, states for an additional 44
characters used in the phylogenetic analysis can be determined.
41(1): Frontals end abruptly anteriorly, suture with nasal
transversely oriented (based on ZIN PH 967/16). This character state
is found in the majority of maniraptorans. It is reversed in some
troodontids and a few other theropod taxa, such as Austroraptor
among dromaeosaurids.
42(1): Anterior emargination of supratemporal fossa on frontal
strongly sinusoidal and reaching onto postorbital process (based on
ZIN PH 967/16). This apomorphic state is present in all known
dromaeosaurids except Austroraptor.
43(1): Frontal postorbital process sharply demarcated from
orbital margin in dorsal view (based on ZIN PH 967/16). The apo-
morphic state is found in dromaeosaurine and velociraptorine
dromaeosaurids and in tyrannosaurids.
44(1): Frontal edge notched (based on ZIN PH 967/16). The
derived state is present in dromaeosaurines, velociraptorines, and
the unenlagiine Austroraptor.
69(0): Labial surface of dentary flat (based on ZIN PH 2338/16).
The apomorphic state, a labial face of the dentary with a labial ridge
and inset tooth row, is present only in therizinosauroids.
71(0): Nutrient foramina on external surface of dentary super-
ficial (based on ZIN PH 2338/16). In some birds, troodontids,
unenlagiine dromaeosaurids, and Shanag, the nutrient foramina are
situated within a deep groove.
82(0): Maxilla toothed (based on CCMGE 600/12457 and ZIN PH
357/16). An edentulous maxilla is present in ornithomimids, ovir-
aptorosaurs, and most birds.
83(0): Maxillary and dentary teeth serrated (based on isolated
teeth). The coding of this character is conditional and conservative.
We cannot rule out that certain teeth from Dzharakuduk without
denticles along the mesial carina also belong to Itemirus (state 2 of
this character).
84(0): Dentary and maxillary teeth large. The coding of this
character is an estimate based on maxillary and dentary fragments
(CCMGE 600/12457, ZIN PH 357/16 and 2338/16). Small teeth, up to
30 in each dentary, are known in unenlagiine dromaeosaurids,
troodontids, some birds, therizinosaurs, and alvarezsaurids.
85(0): Dentary teeth in separate alveoli (based on ZIN PH 2338/
16). The dentary teeth are set in an open groove in troodontids.
86(1): Serration denticles small (based on isolated teeth). This
state is present in most theropods except therizinosauroids and
derived troodontids.
87(0): Serrations simple, denticles convex (based on isolated
teeth). Hooked denticles are present in derived troodontids.
88(1): Teeth, root and crown confluent (based on isolated teeth).
The opposite state, teeth with a constriction between root and
crown, is characteristic for alvarezsaurids, therizinosauroids, birds,
and troodontids.
90(0): Dentary without distinct interdental plates (based on ZIN
PH 2338/16). This character state is present in dromaeosaurids and
troodontids.
95(0): Epipophyses of cervical vertebrae placed distally on
postzygapophyses, above postzygapophyseal facets (based on
ZIN PH 92/16). The apomorphic state, with epipophyses placed
proximal to postzygapophyseal facets, is occasionally found
among theropods. Most dromaeosaurids retain the plesiomor-
phic state.
96(0): Anterior cervical centra level with or shorter than pos-
terior extent of neural arch (based on ZIN PH 92/16). Reversal to this
plesiomorphic state is characteristic for all known dromaeosaurids
except Buitreraptor. In troodontids and more distant theropods, the
centra extend beyond posterior end of the neural arch.
98(1): Anterior cervical centra distinctly wider than high,
kidney-shaped (based on ZIN PH 92/16). This is a synapomorphy for
Maniraptoriformes (Maniraptora þOrnithomimidae).
99(1): Cervical neural spines short and centered on neural arch,
lending the arch an X shape in dorsal view (based on ZIN PH 92/16
and 90/16). This is a synapomorphy for Coelurosauria with few
reversals.
100(0): Cervical centra with one pair of pneumatic openings
(based on ZIN PH 92/16 and 90/16). The apomorphic state, with two
pairs of pneumatic openings on cervical centra, is occasionally
found in oviraptorosaurs, troodontids, and birds.
101(0): Cervical and anterior dorsal vertebrae amphiplatyan
(based on ZIN PH 92/16, 90/16, and 13/16). Among Coelurosauria,
opisthocoelous cervicals and anterior dorsals are present in the
basal tyrannosauroid Dilong and some alvarezsaurids, whereas
birds have at least partially heterocoelous centra.
102(1): Anterior dorsal vertebrae with large hypapophyses
(based on ZIN PH 13/16). This is a synapomorphy for Maniraptora
with some reversals, notably among birds. Among known dro-
maeosaurids, prominent hypapophyses on anterior dorsals are
absent only in Microraptor.
103(1): Parapophyses of posterior dorsal vertebrae distinctly
projected on pedicles (based on ZIN PH 2269/16). The derived state
is present in dromaeosaurids and alvarezsaurids.
104(1): Hyposphene-hypantrum articulations in dorsal verte-
brae present (based on ZIN PH 2269/16). This character is found in
most coelurosaurs except derived alvarezsaurids and birds.
105(1): Zygapophyses of dorsal vertebrae lateral to neural canal
and separated by groove for interspinous ligaments, with hypo-
sphenes separated (based on ZIN PH 13/16, 73/16, and 2269/16). A
synapomorphy for Maniraptora, reversed in Alxasaurus.
117(1): Anterior caudal centra box-like (based on ZIN PH 2273/
16). This is a synapomorphy for Oviraptorosauria þParaves,
reversed in caenagnathids.
119(1): Neural spines on distal caudals absent (based on ZIN
PH 2346/16). This is a synapomorphy for Paraves, with further
modification in troodontids (midline sulcus in center of neural
arch).
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 237

Fig. 14. Strict consensus trees of 2,048 and 2,049 most parsimonious trees, respectively, showing relationships among Dromaeosauridae including Itemirus. Analyses were undertaken using the TNT new technology search algorithm
and the character-taxon matrix compiled by Turner et al. (2012), with added data for Itemirus medullaris scored for the holotype only (A) and combining data from the holotype and referred specimens reported in this paper (B).
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240238

204(1): Ungual and penultimate phalanx of pedal digit II:
penultimate phalanx highly modified for extreme hyperextension,
ungual more strongly curved and significantly larger than that of
digit III. The structure of the penultimate phalanx is known from
ZIN PH 11/16, but no second and third pedal unguals have been
found to date. A synapomorphy for Deinonychosauria.
213(0): Distal articular ends of metacarpals I and II ginglymoid
(based on ZIN PH 182/16 and 183/16). The round articular ends of
metacarpals I and II are derived in ornithomimids and
Sinornithosaurus.
220(0): Dentary fully toothed (based on ZIN PH 2338/16). The
plesiomorphic state is present in all deinonychosaurians.
228(1): Flexor heel on pedal phalanx II-2 long and lobate, with
extension of midline ridge extending onto its dorsal surface (based
on ZIN PH 11/16). This state independently evolved in derived
troodontids and dromaeosaurids.
238(1): Jugal process of maxilla, ventral to external antorbital
fenestra, dorsoventrally wide (based on CCMGE 600/12457 and ZIN
PH 357/16). This apomorphic state is occasionally present among
dromaeosaurids. We coded Itemirus for this character state based
on comparison with Dromaeosaurus (Currie, 1995,fig. 2).
245(1): Supratemporal fossa covers most of the frontal process
of the postorbital and extends anteriorly onto dorsal surface of
frontal (based on ZIN PH 967/16). The apomorphic state is charac-
teristic for most dromaeosaurids, tyrannosaurids, and a few other
theropod taxa.
247(1): Anterior (mesial) denticles of teeth, when present,
significantly smaller than posterior (distal) denticles (based on
isolated teeth). The apomorphic state is present in all dromaeo-
saurids except Dromaeosaurus.
264(1): Prezygapophyses in anterior postaxial cervicals ante-
roposteriorly convex, flexed ventrally anteriorly (based on ZIN PH
92/16). A synapomorphy for Coelurosauria except Tyrannosauridae.
265(2): Pleurocoels present in all dorsals (based on ZIN PH 13/
16, 73/16, 2269/16 and other specimens). This apomorphic state
evolved independently in several theropod lineages and is char-
acteristic for most dromaeosaurids.
316(0): Thoracic vertebrae, parapophyses rostral to transverse
processes (based on ZIN PH 13/16, 73/16, and 2269/16). The apo-
morphic condition, parapophyses ventral to transverse processes, is
found in some birds.
317(0): Thoracic vertebrae, centra approximately equal in length
and midpoint width (based on ZIN PH 13/16, 73/16, and 2269/16).
The distribution of a derived state, centrum length markedly
greater than midpoint width, shows no obvious pattern of phylo-
genetic distribution.
318(2): Thoracic vertebrae, lateral surfaces of centra with central
ovoid foramina (based on ZIN PH 13/16, 73/16, and 2269/16). The
distinction between the two derived character states, deep, emar-
ginated fossae (state 1) and central ovoid foramina (state 2), is
somewhat ambiguous. Among dromaeosaurids, Rahonavis and
Bambiraptor were coded as having state 1 and only Balaur was
coded as having state 2. In ZIN PH 73/16, 2269/16, and other
vertebrae from Dzharakuduk, the pleurocoel is centrally placed,
ovoid and deep, as in Balaur (Brusatte et al., 2013,fig. 6B). Thus, we
code Itemirus as having state 2.
392(0): Metacarpal I, anteroproximally projected muscular
process absent (based on ZIN PH 182/16). The derived states of this
character are found in birds.
393(0): Metacarpal I, anterior surface roughly hourglass-shaped
proximally, at least moderately expanded anteroposteriorly, and
constricted just before flare of articulation for phalanx 1 (based on
ZIN PH 182/16). The apomorphic state, anterior surface broadly
convex, is present in some birds.
456(0): Pedal phalanx II-2, distal articular surface approxi-
mately equal in size or slightly smaller of proximal articular surface
(based on ZIN PH 11/16). The derived state is a synapomorphy for
troodontids.
463(0): Notch for postorbital contact on postorbital process of
frontal absent, process smooth or facet small (based on ZIN PH 967/
16). A large notch is present in derived troodontids.
464(0): Position of frontoparietal suture relative to postorbital
processes of frontal, well posterior to the postorbital processes
(based on ZIN PH 967/16). All known dromaeosaurids except for
Mahakala show reversal to this plesiomorphic state.
465(1): Articular surfaces between cervical vertebrae strongly
slanted anteroventrally (based on ZIN PH 92/16). This is a synapo-
morphy for Deinonychosauria þOviraptorosauria and reversed in
birds.
Two analyses were performed. In the first, the terminal taxon
Itemirus medullaris included only 14 characters that could be scored
for the holotype. In the second analysis, we used the combined
scoring for the holotype and all referred specimens, with a total of
58 characters (12.2% of the characters used in the data matrix). In
the first analysis, employing the new technology search algorithm
of TNT (Goloboff et al., 2003) yielded six most parsimonious trees,
each with a length of 2,048 steps, a consistency index of 0.29, and a
retention index of 0.73 (Fig. 14A). The second analysis with the
same settings generated six most parsimonious trees with a length
of 2,049 steps, a consistency index of 0.29, and a retention index of
0.73 (Fig. 14B). The strict consensus tree was constructed using
Winclada version 1.00.08 interface (Nixon, 1999). In both analyses,
Itemirus is recovered as a member of an unresolved grouping
Dromaeosaurinae, comprising Dromaeosaurus,Atrociraptor,Utah-
raptor, and Achillobator.
5. Conclusions
We report on skeletal remains of dromaeosaurid theropods
from the richly fossiliferous continental strata of the Upper Creta-
ceous (Turonian) Bissekty Formation of the Kyzylkum Desert in
Uzbekistan. Our re-examination of the first published specimen, a
partial braincase designated as the holotype of Itemirus medullaris
Kurzanov, 1976, supports its attribution to Dromaeosauridae, spe-
cifically Dromaeosaurinae. Additional, mostly well-preserved
skeletal remains from the Bissekty Formation, including cranial
bones, teeth, vertebrae, and some podial elements, are tentatively
referred to the same taxon, Itemirus medullaris. They establish the
presence of dromaeosaurid paravians in present-day Central Asia
during the Turonian epoch. Although its attribution to Itemirus is
uncertain an isolated pedal phalanx II-2 (ZIN PH 11/16) indicates
the presence of very large dromaeosaurids, comparable in size to
Utahraptor from the Lower Cretaceous (Barremian) Cedar Mountain
Formation of Utah (Kirkland et al., 1993). The Bissekty Formation
has also yielded skeletal remains of a medium-sized tyrannosau-
roid theropod (Averianov and Sues, 2012b), raising the interesting
question how the two similar-sized predators partitioned the role
of apex predator in this rich Turonian-age ecosystem.
Acknowledgments
Fieldwork in Uzbekistan was facilitated by and conducted in
cooperation with the Zoological Institute of the National Academy
of Sciences of Uzbekistan, particularly D.A. Azimov and Y.A. Chikin.
For their efforts in the field, scientific expertise, and camaraderie,
we thank A.V. Abramov, J.D. Archibald, G.O. Cherepanov, I.G. Dan-
ilov, S. Dominguez, C. King, N. Morris, C.M. Redman, A.S. Resvyi, C.
Skrabec, P.P. Skutschas, E.V. Syromyatnikova, and D.J. Ward. We are
H.-D. Sues, A. Averianov / Cretaceous Research 51 (2014) 225e240 239

indebted to V.R. Alifanov (Borissiak Paleontological Institute,
Russian Academy of Sciences, Moscow) for granting access to the
holotype of Itemirus medullaris. We gratefully acknowledge finan-
cial support from the National Science Foundation (EAR-9804771
and EAR-0207004 to J.D. Archibald and H.-D. Sues), the National
Geographic Society (#5901-97 and #6281-98 to J.D. Archibald and
H.-D. Sues), the Navoi Mining and Metallurgy Combinat, the
Civilian Research and Development Foundation (RU-G1-2571-ST-
04 and RUB1-2860-ST-07), the Russian Fund of Basic Research (07-
04-91110-AFGIRa), and the Russian Scientific Fund (14-14-00015).
We thank two anonymous reviewers and Editor-in-Chief E. Kout-
soukos for helpful comments on a draft of the manuscript.
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