[Paleontology • 2024] Hypnovenator matsubaraetoheorum • Early Cretaceous troodontine troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan reveals the early Evolution of Troodontinae

Hypnovenator matsubaraetoheorum

 Kubota, Kobayashi & Ikeda, 2024

DOI: 10.1038/s41598-024-66815-2 

 Researchgate.net/publication/382559642

Abstract

A new troodontid dinosaur, Hypnovenator matsubaraetoheorum gen. et sp. nov., is described based on an articulated postcranial skeleton recovered from the fluvial deposits of the Albian Ohyamashimo Formation of the Sasayama Group in Tambasasayama City, Hyogo Prefecture, Japan. Hypnovenator is distinguished from other troodontids by four autapomorphies and a combination of additional features. Our phylogenetic analysis positions Hypnovenator as the oldest and one of the most basal troodontines, forming a clade with Gobivenator mongoliensis. The discovery of Hypnovenator suggests that small-bodied maniraptorans with a sleeping posture were common not only in environments with volcanic and eolian events or alluvial systems but also in fluvial systems. Geometric morphometric analysis of manual ungual phalanges shows that manual ungual phalanges I and III of Hypnovenator exhibit considerable morphological variation but are functionally similar, which differs from those of non-troodontine troodontids, reflecting the transition of manual motion within Troodontinae. Hypnovenator also has mosaic features in the pes related to cursoriality. This study reveals that asymmetrical arctometatarsus occurred by the Albian, and some morphological changes, such as shorter digit IV than digit III and non-ungual phalanges of digits III with roller joints and digit IV with weakly ginglymoid articulation, arose during the early Late Cretaceous.

Keywords: Arctometatarsus, Geometric morphometric analysis, Sleeping posture, Theropoda, Troodontidae, Troodontinae, 

Hypnovenator matsubaraetoheorum gen. et sp. nov.
 Blocks including the forelimb, knee (A), and heel (B). (C) Reconstructed skeleton. Red and yellow colors show the confirmed and probable positions of the recovered elements, respectively (Courtesy of Genya Masukawa). (D) Left manus in medial view. (E) Left manual phalanx I-1 in dorsal view. (F) Removed fragmentary left manual phalanx II-3 (manual ungual phalanx II) for preparing the left manus. (G) Cross-section of the bent right ankle. (H) Left metatarsus in posterior view. 

 Abbreviations: as, astragalus; dp, depression; fe, femur; fi, fibula; hu, humerus; mc I, metacarpal I; mc II, metacarpal II; mc III, metacarpal III; mp I-1, manual phalanx I-1; mp I-2, manual phalanx I-2 (manual ungual phalanx I); mp II-1, manual phalanx II-1; mp II-3, manual phalanx II-3 (manual ungual phalanx II); mp III-3, manual phalanx III-3; mp III-4, manual phalanx III-4 (manual ungual phalanx III); mr, medial ridge; mt II, metatarsal II; mt III, metatarsal III; mt IV, metatarsal IV; mt V, metatarsal V; ra, radius; ti, tibia; ul, ulna. Almost all elements are from the left side. Abbreviations for elements from the right side added ‘(r)’ at the end. 

Systematic paleontology

Theropoda  

Coelurosauria 

Troodontidae 

Hypnovenator matsubaraetoheorum gen. et sp. nov.

Diagnosis: A troodontid with the following unique characters: a pair of proximodistally extended depressions on the proximodorsal surface of manual phalanx I-1; long dorsal and ventral proximal lips on manual phalanx III-2 for tight articulation with phalanx III-1; a proximodistally longitudinal medial ridge on the anterior surface of the femur proximal to the medial condyle; and distorted distal condyles with a widely convex distoventral margin on pedal phalanx III-3. Additionally, it is characterized by the following combination of two features: the thickest portion near the middle portion of the distal end of the ulna, and an angle of less than 11 degrees between the anterior edge of the cnemial crest and the anterior edge of the tibial shaft.

Locality and horizon: Hyogo Prefectural Tamba Namikimichi Central Park at Nishikosa, Tambasasayama City, Hyogo Prefecture, Japan; the early to middle Albian (112.1–106.4 Ma26) Ohyamashimo Formation of the Sasayama Group.

Etymology: The genus name derives from “hypno”, refers to “sleep” in ancient Greek, and “venator”, means “hunter” in Latin. The specific name, “matsubaraetoheorum”, honors Mrs. Kaoru Matsubara and Takaharu Ohe, who are the first discoverers of a block including a part of Hypnovenator matsubaraetoheorum holotype specimen.

 

Katsuhiro Kubota, Yoshitsugu Kobayashi and Tadahiro Ikeda. 2024. Early Cretaceous troodontine troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan reveals the early evolution of Troodontinae. Scientific Reports. 14: 16392. DOI: doi.org/10.1038/s41598-024-66815-2

  Researchgate.net/publication/382559642_Early_Cretaceous_troodontid_from_the_Ohyamashimo_Formation_of_Japan

[Paleontology • 2024] Harenadraco prima • The first troodontid (Theropoda: Troodontidae) from the Upper Cretaceous Baruungoyot Formation of Mongolia

  

Harenadraco prima

S. Lee, Y.-N. Lee, Park, Kim, Badamkhatan, Idersaikhan & Tsogtbaatar, 2024

 

 DOI: 10.1080/02724634.2024.2364746 

artwork by Yusik Choi

ABSTRACT

Among non-avian dinosaurs, troodontids are relatively rare but diverse. The Nemegt Basin in the Mongolian Gobi Desert, which incorporates three of the most fossiliferous beds in the world, is one such region with high troodontid diversity and has also produced eight troodontid taxa until now. The diversity of troodontids is biased towards the two formations, Nemegt and Djadochta. Despite its rich vertebrate fossil record, no troodontids have been described from the Baruungoyot Formation. This faunal absence is perplexing as the Baruungoyot Formation has often been considered intermediate between the other two units in stratigraphy and paleoenvironment, but there are no definite troodontid materials that could fill this ‘gap.’ Here, we report a new troodontid, Harenadraco prima gen. et sp. nov., from the Baruungoyot Formation in Hermiin Tsav, Mongolia. It is represented by an incomplete skeleton that mainly consists of partially articulated left hind limb elements. Harenadraco is small and lightly built like other troodontids, but its tarsometatarsus exhibits extreme slenderness comparable only to Philovenator among cursorial non-avian maniraptorans. It also implies high cursoriality that could be an adaptation of Harenadraco to its environment where potential prey animals like mammals and predators such as eudromaeosaurs were likely to be agile. The discovery of Harenadraco confirms the presence of troodontids in all three formations in the Nemegt Basin.

 Left pedal phalanges and the skeletal reconstruction of the preserved parts in Harenadraco prima (MPC-D 110/119, holotype). A, left pedal digits II–IV in lateral view. 
 M, skeletal reconstruction of Harenadraco prima (MPC-D 110/119, holotype) with missing parts in gray.

Abbreviations: II-3, pedal phalanx II-3; III-3, pedal phalanx III-3; IV-2, pedal phalanx IV-2.

 Life reconstruction of Harenadraco prima 

(artwork by Yusik Choi).

DINOSAURIA Owen, 1842

THEROPODA Marsh, 1881

TROODONTIDAE Gilmore, 1924

HARENADRACO PRIMA, gen. et sp. nov.

Diagnosis—A small-sized troodontid diagnosed by the following unique combination of characters (autapomorphies indicated with an asterisk): tall S-shaped medial margin of medial condyle of astragalocalcaneum in anterior view*, poorly developed flexor sulcus on the distal articular end of metatarsal II, which also lacks collateral ligament fossae*, metatarsal III excluded from the proximal end of the metatarsus in dorsal view (shared with Tochisaurus, Zanabazar, and Philovenator), metatarsal IV only slightly more robust than metatarsal II at the proximal end in ventral view (shared with Daliansaurus and Philovenator), pronounced ventral protrusion near the proximal end of metatarsal IV (shared with Liaoningvenator), extremely narrow proximal shaft of metatarsal IV*, greatly elongated flexor tubercle of pedal phalanx II-3 that reaches the shaft of the preceding phalanx when in articulation*, and the distal articular surface of pedal phalanx III-3 not ginglymoid*.

Etymology—The name of the genus is a composition of the Latin words harena (sand) and draco (dragon). The species name “prima” means first in Latin, referring to the taxon being the first troodontid from the Baruungoyot Formation.

 

Sungjin Lee, Yuong-Nam Lee, Jin-Young Park, Su-Hwan Kim, Zorigt Badamkhatan, Damdinsuren Idersaikhan and Khishigjav Tsogtbaatar. 2024. The first troodontid (Dinosauria: Theropoda) from the Upper Cretaceous Baruungoyot Formation of Mongolia. Journal of Vertebrate Paleontology. e2364746. DOI: doi.org/10.1080/02724634.2024.2364746  

[Paleontology • 2021] The Phylogenetic Affinities and Morphological Peculiarities of the Bird-like Dinosaur Borogovia gracilicrus (Maniraptora: Troodontidae) from the Upper Cretaceous of Mongolia

Borogovia gracilicrus  Osmólska, 1987

in Cau​ & Madzia, 2021.

DOI: 10.7717/peerj.12640 

Artwork by Edyta Felcyn-Kowalska

 twitter.com/DanielMadzia 

 theropoda.blogspot.com 

Abstract 

Borogovia gracilicrus is a small-bodied theropod dinosaur from the Maastrichtian (Upper Cretaceous) Nemegt Formation of southern Mongolia. The taxon is based on a single fragmentary specimen preserving only the distal part of the hindlimbs. The morphology of Borogovia shows a peculiar combination of features, some of which are traditionally considered troodontid synapomorphies and others which are unusual for Troodontidae but are shared with other maniraptoran clades. In particular, the second toe of B. gracilicrus differs from other troodontids in lacking some of the features which contribute to the specialized ‘sickle-clawed’ second toe, here termed the ‘falciphoran condition’, shared with dromaeosaurids and some other paravians, such as the strongly compressed and falciform ungual. Phylogeny reconstructions intended to explore the affinities of Borogovia consistently support its referral within a subclade of troodontids including all Late Cretaceous taxa. The placement of Borogovia is not significantly affected by its unusual combinations of hindlimb features or by the homoplasy of the elements forming the falciphoran condition. Borogovia is supported as a valid taxon and is distinct from the other Nemegt troodontids, Tochisaurus and Zanabazar. The lack of a falciform ungual, and the distinctive morphology of the second toe in B. gracilicrus are interpreted as a derived specialization among Troodontidae and not as retention of the plesiomorphic condition of non-paravian theropods.

Theropoda Marsh, 1881 [Naish et al., 2020]

Paraves Sereno, 1997

Troodontidae Gilmore, 1924

Borogovia gracilicrus Osmólska, 1987

 

Conclusions: 

Borogovia gracilicrus is a troodontid dinosaur from the Nemegt Formation of Mongolia. Although overlapping material with the other Nemegt trooodontids (Tochisaurus nemegtensis and Zanabazar junior) is limited, Borogovia can be differentiated from these taxa based on the unique combination of features in its tibiotarsus and metatarsus.

The phylogenetic position of B. gracilicrus among Maniraptora is investigated in detail for the first time. This taxon is robustly supported as a member of Troodontidae, and reconstructed among non-troodontine troodontids. These results are not biased by a priori assumptions on character weighting.

The foot of Borogovia is autapomorphic and combines troodontid synapomorphies (e.g., the arctometatarsus) and the secondary loss of some elements of the falciphoran condition widespread among paravians. In particular, the morphology of the second toe of Borogovia might indicate an ecological niche distinct from those of other ‘deinonychosaur-grade’ paravians. Such a scenario could account for the co-occurrence of several troodontids in the paleofauna of the Nemegt Formation.

Andrea Cau​ and Daniel Madzia. 2021. The Phylogenetic Affinities and Morphological Peculiarities of the Bird-like Dinosaur Borogovia gracilicrus from the Upper Cretaceous of Mongolia. PeerJ.  9: e12640. DOI: 10.7717/peerj.12640.  

 twitter.com/DanielMadzia/status/1467829316146929678

 theropoda.blogspot.com/2021/12/borogovia-reloaded.html

[Paleontology • 2021] The Early Origin of A Birdlike Inner Ear and the Evolution of Dinosaurian Movement and Vocalization

in Hanson, Hoffman, Norell et Bhullar, 2021.

DOI: 10.1126/science.abb4305 

 twitter.com/AnjanBhullar 

Abstract

Reptiles, including birds, exhibit a range of behaviorally relevant adaptations that are reflected in changes to the structure of the inner ear. These adaptations include the capacity for flight and sensitivity to high-frequency sound. We used three-dimensional morphometric analyses of a large sample of extant and extinct reptiles to investigate inner ear correlates of locomotor ability and hearing acuity. Statistical analyses revealed three vestibular morphotypes, best explained by three locomotor categories—quadrupeds, bipeds and simple fliers (including bipedal nonavialan dinosaurs), and high-maneuverability fliers. Troodontids fall with Archaeopteryx among the extant low-maneuverability fliers. Analyses of cochlear shape revealed a single instance of elongation, on the stem of Archosauria. We suggest that this transformation coincided with the origin of both high-pitched juvenile location, alarm, and hatching-synchronization calls and adult responses to them.

 Michael Hanson, Eva A. Hoffman, Mark A. Norell and Bhart-Anjan S. Bhullar. 2021. The Early Origin of A Birdlike Inner Ear and the Evolution of Dinosaurian Movement and Vocalization. Science. 372, 6542. 601-609. DOI: 10.1126/science.abb4305

  twitter.com/AnjanBhullar/status/1390465252672823297

 

 Jonah N. Choiniere, James M. Neenan, Lars Schmitz, David P. Ford, Kimberley E. J. Chapelle, Amy M. Balanoff, Justin S. Sipla, Justin A. Georgi, Stig A. Walsh, Mark A. Norell, Xing Xu, James M. Clark and Roger B. J. Benson. 2021. Evolution of Vision and Hearing Modalities in Theropod Dinosaurs. Science. 372, 6542; 610-613. DOI: 10.1126/science.abe7941

  twitter.com/Kimi_Chap/status/1390411550071132167

 

Revealing behavioral secrets in extinct species

Extinct species had complex behaviors, just like modern species, but fossils generally reveal little of these details. New approaches that allow for the study of structures that relate directly to behavior are greatly improving our understanding of the lifestyles of extinct animals (see the Perspective by Witmer). Hanson et al. looked at three-dimensional scans of archosauromorph inner ears and found clear patterns relating these bones to complex movement, including flight. Choiniere et al. looked at inner ears and scleral eye rings and found a clear emergence of patterns relating to nocturnality in early theropod evolution. Together, these papers reveal behavioral complexity and evolutionary patterns in these groups.

[Paleontology • 2021] Tamarro insperatus • A Fast-growing Basal Troodontid (Theropoda: Maniraptora) from the latest Cretaceous of Europe

 

Tamarro insperatus  

Sellés, Vila, Brusatte, Currie & Galobart, 2021

 DOI: 10.1038/s41598-021-83745-5

Abstract

A characteristic fauna of dinosaurs and other vertebrates inhabited the end-Cretaceous European archipelago, some of which were dwarves or had other unusual features likely related to their insular habitats. Little is known, however, about the contemporary theropod dinosaurs, as they are represented mostly by teeth or other fragmentary fossils. A new isolated theropod metatarsal II, from the latest Maastrichtian of Spain (within 200,000 years of the mass extinction) may represent a jinfengopterygine troodontid, the first reported from Europe. Comparisons with other theropods and phylogenetic analyses reveal an autapomorphic foramen that distinguishes it from all other troodontids, supporting its identification as a new genus and species, Tamarro insperatus. Bone histology shows that it was an actively growing subadult when it died but may have had a growth pattern in which it grew rapidly in early ontogeny and attained a subadult size quickly. We hypothesize that it could have migrated from Asia to reach the Ibero-Armorican island no later than Cenomanian or during the Maastrichtian dispersal events.

Geographic and geological location of Sant Romà d’Abella site. Geographic location of the Tremp Syncline in the southern Pyrenean region (A). Geological map of the eastern part of the Tremp Syncline with the location of the Sant Romà d’Abella site (B). Landscape view of the fossil site (C) with a detailed picture showing the close spatial relationship between the troodontid metatarsal (MCD-7073) and axial elements of Pararhabdodon isonensis (D). Stratigraphic section at Sant Romà d’Abella area with the precise position of the fossiliferous Sant Romà d’Abella site (E).

The European troodontid Tamarro insperatus (MCD-7073) gen. et sp. nov. from the uppermost Maastrichtian of the Tremp Group, Tremp Basin, Southern Pyrenees. Photographic and interpretative ilustrations of the right second metatarsal in anterior (A-A’), lateral (B-B’), posterior (C–C’), medial (D-D’), and distal (F-F’) views. Scheme illustrating the gradual transition of the articular surface–grey arrow–for the accommodation of the metatarsal III (E). Detail of the distal end of the metatarsal II in anterior view showing the anterior contact surface of the metatarsal III (G). Detail of the articular surface of the metatarsal IV in the posterodistal part of the second metatarsal (H) ant anterior; f foramen; lat lateral; lc medial condyle; mc, lateral condyle; II–III contact between the second and third metatarsals; II–IV contact between the second and fourth metatarsals; plr plantar ridge; s sulcus.

      

Systematic palaeontology

Dinosauria Owen, 1842

Theropoda Marsh, 1881

Coelurosauria Huene, 1914

Maniraptora Gauthier, 1986

Troodontidae Gilmore 1924

? Jinfengopteryginae Turner, Makovicky, and Norell, 2012

Tamarro insperatus gen. et sp. nov.

 

Etymology: Tamarro, Catalan word referring to a small and elusive fantastic creature from the regional (Pallars county) folklore. Insperatus, from the Latin word for “unexpected”, in reference to the unexpected discovery of the specimen.

Holotype: MCD-7073, a partial right metatarsal II.

Diagnosis: Tamarro insperatus is a mid-sized basal troodontid distinguished by the following unique combination of characters (* marks potential autapomorphies): metatarsal II with marked plantar ridge; small foramen on the lateral surface of the plantar ridge of the metatarsal II*; sub-arctometatarsalian condition with the metatarsal III restricted to the plantar margin on its proximal part.

Type locality and age: Sant Romà d’Abella locality (Pallars Jussà, Catalonia); upper part of the Talarn Formation of the Tremp Group. The site is correlated with the C29r magnetochron14, latest Maastrichtian age.

Conclusions: 

The discovery of the new basal troodontid Tamarro insperatus at the very end of the Cretaceous in Europe represents the first evidence of bones of Troodontidae in Europe. Both phylogenetic and osteohistological results support the basal nature of the new taxon, most likely as a representative of the Asian clade Jinfengopteryginae. The histological analysis also has provided evidence for a mature individual with a high growth rate, which allowed the animal to attain subadult body size in a very short time. This growth strategy is similar to other basal troodontids, such as the Asian Mei long.

The fragmentary, yet controversial, record of troodontid-like teeth from Europe together with the likely Asian affinity of Tamarro, confirm that troodontids could have reached the ancient European Archipelago during the Late Cretaceous. Furthermore, the relatively large size of Tamarro insperatus compared with its closest phylogenetic relatives suggests it would be the largest among jinfengopterygines.

 

Albert G. Sellés, Bernat Vila, Stephen L. Brusatte, Philip J. Currie and Àngel Galobart. 2021. A Fast-growing Basal Troodontid (Dinosauria: Theropoda) from the latest Cretaceous of Europe. Scientific Reports. 11: 4855. DOI: 10.1038/s41598-021-83745-5

[Paleontology • 2019] Hesperornithoides miessleri • A New Paravian Dinosaur from the Late Jurassic of North America supports A Late Acquisition of Avian Flight

Hesperornithoides miessleri 

Hartman, Mortimer, Wahl, Lomax, Lippincott & Lovelace, 2019

 DOI: 10.7717/peerj.7247

Illustration by Gabriel Ugueto twitter.com/SerpenIllus

Abstract 

The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the origin of avialan flight. Here, we describe Hesperornithoides miessleri gen. et sp. nov., a new paravian theropod from the Morrison Formation (Late Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen comprising a partial, well-preserved skull and postcranial skeleton. Limb proportions firmly establish Hesperornithoides as occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close to Daliansaurus, Xixiasaurus, and Sinusonasus. Multiple alternative paravian topologies have similar degrees of support, but proposals of basal paravian archaeopterygids, avialan microraptorians, and Rahonavis being closer to Pygostylia than archaeopterygids or unenlagiines are strongly rejected. All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.

Figure 3: Reconstructed quarry map of WYDICE-DML-001. Association of skeletal elements assembled from 3D scans of specimen blocks prior to final mechanical preparation. Scale bar = 6 cm.

Figure 4: Primary blocks of WYDICE-DML-001. “Left” (A) and “right” (B) sides of the blocks after final preparation (B). Scale bar = one cm. Images taken by Levi Shinkle

Systematic Palaeontology

Theropoda Marsh, 1881

Maniraptora Gauthier, 1986

Paraves Sereno, 1997

Deinonychosauria Colbert & Russell, 1969

Troodontidae Gilmore, 1924

Hesperornithoides miessleri gen. et sp. nov.

Holotype: WYDICE-DML-001 (Wyoming Dinosaur Center, Thermopolis), a single, partially articulated skeleton consisting of most of an articulated skull and mandibles missing the anteriormost portions, hyoids, five cervical vertebrae, first dorsal vertebra, isolated anterior dorsal rib, portions of 12 caudal vertebrae, five chevrons, partial left scapula and coracoid, portions of the proximal left humerus and distal right humerus, left ulna and radius, radiale, semilunate carpal, left metacarpals I–III, manual phalanges III-2 and 3, manual unguals I, II, and III, ilial fragment, most of an incomplete femur, right and left tibiae and fibulae, left astragalus and calcaneum, portions of right and left metatarsal packets, left pedal phalanges III-1, III-2, III-3, IV-1, IV-2, IV-3, IV-4, and pedal unguals II and III and the proximal portion of IV.

Etymology: “Hesper,” (Greek) referring to the discovery in the American West, “ornis,” (Greek) for bird and “oeides,” (Greek) for similar, referring to the avian-like form of derived paravians. The trivial epithet honors the Miessler family, who have been avid supporters of the project.

Occurrence: Douglas, Converse County, Wyoming, USA; middle portion of Morrison Formation, which has been variously dated between Oxfordian and Tithonian in age (Trujillo, 2006; Trujillo et al., 2014), associated vertebrate fossils include the sauropod Supersaurus, a stegosaurid plate, and isolated large theropod teeth.

Diagnosis: A paravian with the following derived characters: pneumatic jugal (also in Zanabazar and some eudromaeosaurs among maniraptorans); short posterior lacrimal process (<15% of ventral process length, measured from internal corner; also present in Zanabazar, Archaeopteryx, and Epidexipteryx); quadrate forms part of lateral margin of paraquadrate foramen; small external mandibular fenestra (<12% of mandibular length; also in Zhenyuanlong and Dromaeosaurus among non-avian paravians); humeral entepicondyle >15% of distal humeral width (also in some avialans); manual ungual III subequal in size to ungual II (also in Daliansaurus, IGM 100/44 and Mahakala); mediodistal corner of tibia exposed anteriorly (also in Archaeopteryx and Jeholornis).

Figure 5: Rigorous skeletal reconstruction of WYDICE-DML-001. Scale bar = 25 cm.

Figure 18: Partially expanded, time calibrated phylogenetic results. Clades containing potentially volant taxa (red) are expanded to show their position nested within flightless taxa (black). Taxa exhibiting aerial locomotion directly connected to crown clade Aves are colored blue. Zhongornis is colored purple to reflect the uncertainty revolving around this juvenile specimen. Barred lineages indicate uncertainty in age (Xiaotingia) or referred taxa (Koparion to troodontids and non-Jehol taxa to Confuciusornithiformes).

Conclusions: 

We have described Hesperornithoides miessleri, a new paravian theropod from the Late Jurassic of North America. We ran a phylogenetic analysis based on previous TWiG datasets with expanded taxonomic sampling and recovered it as a troodontid, the oldest diagnostic specimen from North America known from more than teeth. Hesperornithoides was clearly a non-volant, terrestrial theropod that spent at least a portion of its life in a marginal lacustrine or wetland environment. The terrestrial and flightless lifestyle is consistent with the base of Paraves, and with the base of paravian subclades, suggesting that avian flight evolved within Avialae, most likely in the Late Jurassic or Early Cretaceous.

       

Scott Hartman, Mickey Mortimer, William R. Wahl, Dean R. Lomax, Jessica Lippincott and David M. Lovelace. 2019. A New Paravian Dinosaur from the Late Jurassic of North America supports A Late Acquisition of Avian Flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

Meet Lori, a tiny dinosaur that may help explain how birds evolved flight  on.natgeo.com/2NHQ5RR  @NatGeoScience

 twitter.com/SerpenIllus/status/1148925176287039488

 twitter.com/Dean_R_Lomax/status/1148955705384275968

 twitter.com/john_pickrell/status/1148914447022481408

        

[Paleontology • 2017] Almas ukhaa • A New Late Cretaceous Troodontid from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia

Almas ukhaa

Pei, Norell, Barta, Bever, Pittman & Xu, 2017

  DOI: 10.1206/3889.1 

ABSTRACT

A new troodontid dinosaur, Almas ukhaa, from the Late Cretaceous deposits of the Djadokhta Formation at Ukhaa Tolgod, Mongolia, is described here. The holotype specimen (IGM 100/1323) comprises an almost complete and articulated cranium and partial articulated postcranial skeleton. This specimen has a small body size and a short snout as in basal paravians, but it exhibits a number of derived troodontid features that differentiate Almas ukhaa from the Early Cretaceous troodontids reported from China and unite this new taxon with other Late Cretaceous troodontids. Relative to other troodontids, Almas ukhaa is autapomorphic in the presence of a posteriorly curved pterygoid flange, absence of a lateral groove on the anterior part of the dentary, presence of a distinct spikelike process on the ischium, and elongate chevrons. The eggshell associated with IGM 100/1323 can be assigned to Prismatoolithidae indet. based on the smooth surface, eggshell thickness, and microstructural characteristics, and also preserves attributes similar to Protoceratopsidovum minimum. A unique relationship between Byronosaurus and the perinate troodontids IGM 100/972 and IGM 100/974 is no longer supported based on the new observations of Almas ukhaa and Gobivenator.

FIGURE 2. Skull of IGM 100/1323 in right lateral view.

FIGURE 1. Type specimen of Almas ukhaa, IGM 100/1323.

SYSTEMATIC PALEONTOLOGY

THEROPODA MARSH, 1881

COELUROSAURIA HUENE, 1920

MANIRAPTORA GAUTHIER, 1986

TROODONTIDAE GILMORE, 1924

Almas ukhaa, new taxon

Etymology: Almas is in reference to the wild man or snowman of Mongolian mythology (Rincen, 1964). Ukhaa refers to the locality of Ukhaa Tolgod, discovered in 1993, where the specimen was collected. 

Rui Pei, Mark A. Norell, Daniel E. Barta, G.S. Bever, Michael Pittman and Xing Xu. 2017. Osteology of A New Late Cretaceous Troodontid Specimen from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia. American Museum Novitates. 3889; 1-47.  DOI: 10.1206/3889.1
 digitallibrary.amnh.org/handle/2246/6818
ResearchGate.net/publication/321834802_Osteology_of_a_New_Late_Cretaceous_Troodontid_Specimen_from_Ukhaa_Tolgod_Omnogovi_Aimag_Mongolia

 twitter.com/Synapsida/status/941727444838465536

[Paleontology • 2017] Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with A Description of A Unique New Taxon, Latenivenatrix mcmasterae: Implications for Deinonychosaur Diversity in North America

Latenivenatrix mcmasterae

van der Reest & Currie, 2017 

DOI: 10.1139/cjes-2017-0031 

ABSTRACT

Troodontids are known from Asia and North America, with the most complete specimens from the Jurassic of China and the Cretaceous of Mongolia. North American troodontids are poorly known, and specimens that have been described are isolated elements or partial skeletons with limited material. A new troodontid from the upper Dinosaur Park Formation (upper Campanian) is based on partial skulls, several vertebrae, ribs, gastralia, chevrons, a sacrum, partial pelvis, and partial fore and hind limbs. It is the largest troodontid known, with an estimated height of 180 cm and length of 350 cm. Like other troodontids, it possesses an elongated ambiens process and has a horizontal ventral margin of the postacetabular process. It differs from all other derived troodontids in that the slightly retroverted pubis has a shaft that curves anteroventrally. Some specimens from the Dinosaur Park Formation previously assigned to Troodon are reassigned to the new taxon, including multiple partial crania, an associated dentary and metatarsus, and a partial skeleton. Previously undescribed elements from the lower part of the Dinosaur Park Formation are assigned to the resurrected Stenonychosaurus inequalis. Distinct stratigraphic separation of Stenonychosaurus inequalis and the new taxon indicates a replacement in troodontid fauna, similar to the turnover of large ornithischians in the same formation. The new taxon is phylogenetically more closely related to Mongolian taxa, indicating the replacement of Stenonychosaurus may have been from an earlier Asian form immigrating into North America.

 Latenivenatrix mcmasterae

Life reconstruction by Julius Csotonyi. 

Systematic palaeontology

Theropoda Marsh, 1881

Maniraptora Gauthier, 1986

Troodontidae Gilmore, 1924 sensu Turner et al. 2012

Troodontinae, clade nov.

DEFINITION: The most inclusive clade containing Gobivenator mongoliensis and Zanabazar junior.

DIAGNOSIS: Troodontinae differs from all other more basal troodontids by possessing an elongated ambiens process that is present on the anterior margin of the iliopubic symphysis.

Latenivenatrix gen. nov. 

Latenivenatrix mcmasterae gen. et sp. nov.

ETYMOLOGY: The generic name derives from “latens” (Latin for latent and hiding) and “venatrix” (feminine form in Latin for hunter). “Latent” refers to the taxon having been in multiple collections for nearly 100 years but unrecognized until now. “Hiding” has a similar meaning to latent, but also refers to a predatory animal hiding in cover until a suitable time to attack its prey. “Hunter” refers to it being carnivorous. The specific epithet honours the late mother of the first author, Lynne (McMaster) van der Reest.

 Stenonychosaurus inequalis Sternberg, 1932

Aaron J. van der Reest and Philip J. Currie. 2017. Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with A Description of A Unique New Taxon: Implications for Deinonychosaur Diversity in North America. Canadian Journal of Earth Sciences. 54; xx. DOI: 10.1139/cjes-2017-0031

 Introducing Latenivenatrix mcmasterae, new Troodontid from the DPF published in @CanJEarthSci this morning! Sorry Troodon formosus #invalid

 twitter.com/AaronVDReest/status/894926653855481856

Dino hips discovery unravels species riddle  bit.ly/2ulK0w6 via @ualberta @EurekAlert

Résumé: Les troodontidés connus proviennent d’Asie et d’Amérique du Nord, les spécimens les plus complets provenant du Jurassique de la Chine et du Crétacé de la Mongolie. Les troodontidés nord-américains sont peu connus et les spécimens décrits consistent en des éléments isolés ou des squelettes partiels représentés par une quantité limitée de matériau. Un nouveau troodontidé de la partie supérieure de la Formation de Dinosaur Park (Campanien supérieur) est basé sur des crânes partiels, plusieurs vertèbres, des côtes, une gastralia, des chevrons, un sacrum, un pelvis partiel et des membres antérieurs et postérieurs partiels. Il s’agit du plus grand troodontidé connu, dont la hauteur est estimée a` 180 cm et la longueur, a` 350 cm. À l’instar d’autres troodontidés, il présente un processus ambiens allongé et une marge ventrale horizontale du processus post-acétabulaire. Il se distingue de tous les autres troodontidés dérivés par son pubis légèrement rétroversé doté d’une diaphyse courbée antéroventralement. Certains spécimens de la Formation de Dinosaur Park auparavant attribués a` Troodon, incluant plusieurs crânes partiels, un os dentaire et un métatarse associés, ainsi qu’un squelette partiel, sont réaffectés au nouveau taxon. Des éléments non décrits auparavant de la partie inférieure de la Formation de Dinosaur Park sont affectés a` Stenonychosaurus inequalis. La séparation stratigraphique claire de Stenonychosaurus inequalis et du nouveau taxon indique un remplacement de la faune de troodontidés semblable au renouvellement des grands ornithischiens de la même formation. Le nouveau taxon est plus étroitement apparenté sur le plan phylogénétique aux taxons de Mongolie, ce qui indique que le remplacement de Stenonychosaurus pourrait être dû a` l’immigration en Amérique du Nord d’une forme asiatique plus ancienne.

[Paleontology • 2017] Albertavenator curriei • A New Species of Troodontid Theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada

Albertavenator curriei 

Evans, Cullen, Larson & Rego, 2017

DOI: 10.1139/CJES-2017-0034 

ABSTRACT

Troodontid material from the Maastrichtian of North America is extremely rare, beyond isolated teeth from microvertebrate sites. Here we describe troodontid frontals from the early Maastrichtian Horseshoe Canyon Formation (Horsethief Member). The most complete specimen, TMP 1993.105.0001, is notably foreshortened and robust when compared with numerous specimens referred to Troodon from the Dinosaur Park Formation, and exhibits several characteristics that distinguish it from other Late Cretaceous troodontids. Morphometric analyses reinforce shape differences between TMP 1993.105.0001 and other North American troodontids, and show that proportional differences are independent of size. We therefore erect a new taxon, Albertavenator curriei gen. et sp. nov., which is diagnosed by the following autapomorphies: (1) primary supraciliary foramen is truncated anteriorly by the lacrimal contact; (2) superficial (ectocranial) surface of the frontal proportionally shorter than all known troodontids, with a length to width ratio under 1.3; and (3) frontoparietal contact in which an enlarged lappet of the frontal extends medially to extensively overlap the lateral region of the anteromedial process of the parietal. Interestingly, tooth and jaw morphology from the single relatively complete dentary recovered from the Horseshoe Canyon cannot be distinguished from dentaries and teeth from the Dinosaur Park Formation. If the dentary and teeth from the Horsethief Member of the Horseshoe Canyon Formation prove to belong to A. curriei, extensive overlap in tooth morphology between the Dinosaur Park and Horseshoe Canyon formations reinforces the notion that tooth morphotypes do not exhibit strong correspondence to species alpha diversity, and may encompass multiple closely related taxa.

Life recreation of Albertavenator curriei.

 Illustrated by Oliver Demuth 

Comparison of 3D frontal models in dorsal, lateral, ventral, medial, anterior, and posterior, respectively, of Albertavenator curriei (top) and Troodon inequalis.

Abbreviations: fc – frontal midline contact, lc – lacrimal contact with frontal, lcb – lacrimal buttress, lsc – laterosphenoid contact with frontal, nc – nasal contact with frontal, or – orbital rim, pc – parietal contact with frontal, pl – parietal lappet, poc – postorbital contact with frontal, scf – supraciliary foramen. Scale bar – 1 cm. 

DOI: 10.1139/cjes-2017-0034 

 .   

David C. Evans, Thomas M. Cullen, Derek W. Larson and Adam Rego. 2017. A New Species of Troodontid Theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada.
 Canadian Journal of Earth Sciences. DOI: 10.1139/cjes-2017-0034

Albertavenator curriei: New Species of Bird-Like Dinosaur Identified in Canada || 

Sci-News.com  sci-news.com/paleontology/albertavenator-curriei-05048.html

Scientists name new species of dinosaur after Canadian icon http://phy.so/419501502 via @physorg_com

https://dinomuseum.ca/media/releases/scientists-name-new-species-dinosaur-canadian-icon/

twitter.com/CurrieMuseum/status/886924395926532096

twitter.com/DavidEvans_ROM/status/886937334813425665

twitter.com/Cullen_Thomas/status/886929747879526401

twitter.com/TheReal_DLarson/status/886917981950717952

twitter.com/OliverDemuth/status/887065382300913664