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Maniraptora

Maniraptora is a diverse clade of coelurosaurian theropod dinosaurs that includes modern birds (Aves) and their closest non-avian relatives, phylogenetically defined as all theropods more closely related to the house sparrow (Passer domesticus) than to the ornithomimid Ornithomimus velox.^[1]^[2] Originating in the Late Jurassic around 150 million years ago, Maniraptora encompasses a wide array of forms from small, feathered predators to large, herbivorous giants, unified by specialized adaptations for grasping and manipulation with their forelimbs, earning the clade its name meaning "hand snatchers."^[1]^[3] The clade is nested within the broader group Coelurosauria and represents one of the most species-rich lineages of dinosaurs, with fossils primarily from Asia and North America spanning the Jurassic to the end of the Cretaceous.^[3]^[2] Key synapomorphies include a half-moon-shaped semilunate carpal bone in the wrist for enhanced mobility, a fused clavicle forming a furcula (wishbone), a downward-rotated pubis, and often a stiffened tail with elongated chevrons.^[1] Many maniraptorans, particularly within the subgroup Paraves, bore feathers, which facilitated insulation, display, and eventually powered flight in birds.^[3]^[2] Maniraptora is subdivided into several major lineages, reflecting its ecological and morphological diversity. Therizinosauria includes bizarre, pot-bellied herbivores like Therizinosaurus cheloniformis with enormous scythe-like claws up to 1 meter long, adapted for foraging vegetation.^[3] Alvarezsauria comprises small, burrowing insectivores such as Mononykus olecranus, featuring reduced forelimbs with powerful, single-clawed hands for digging.^[3] Oviraptorosauria, including Oviraptor philoceratops and the massive Gigantoraptor erlianensis, were likely omnivorous or herbivorous, known from brooding behaviors suggesting parental care.^[1]^[3] The advanced subgroup Eumaniraptora, or Paraves, splits into Deinonychosauria—encompassing agile, sickle-clawed predators like dromaeosaurids (Velociraptor mongoliensis, Deinonychus antirrhopus) and the brainy troodontids (Troodon formosus)—and Avialae, the clade containing all birds.^[1]^[2] The diversification of Maniraptora accelerated in the Early Cretaceous, particularly in the Jehol Biota of China (circa 130–120 million years ago), where feathered specimens reveal a mosaic evolution toward avian traits, including powered flight precursors.^[2] While non-avian maniraptorans went extinct at the end-Cretaceous mass extinction 66 million years ago, birds survived and radiated into over 10,000 species today, underscoring Maniraptora's pivotal role in vertebrate evolution.^[2] Phylogenetic analyses continue to refine relationships within the clade, with debates centering on the exact positions of early avialans like Archaeopteryx relative to deinonychosaurs.^[2]

Description

Defining characteristics

Maniraptora is diagnosed by a suite of skeletal synapomorphies that distinguish it from other coelurosaur theropods, primarily involving modifications to the forelimb, pelvis, and axial skeleton that reflect enhanced agility and predatory capabilities. A key feature is the presence of a furcula, or wishbone, formed by the fusion of the clavicles, which provides structural support for the pectoral girdle and is absent or rudimentary in outgroup taxa such as tyrannosaurids and allosaurids within Tetanurae.^[4] Another defining trait is the semilunate carpal, a half-moon-shaped distal carpal that articulates with metacarpal I and II, enabling the hand to fold against the forearm in a bird-like manner; this structure is unique to Maniraptora and contrasts with the more rigid wrist of basal tetanurans, where the carpal elements lack this specialized morphology.^[4] In many derived maniraptorans, particularly within Eumaniraptora, the manus exhibits marked asymmetry, with digits II and III enlarged and digit I reduced to a small, splint-like element bearing few phalanges; basal groups like alvarezsaurids show the reverse (enlarged digit I, reduced II-III), while therizinosaurs retain a more robust, subequal three-fingered hand, differing overall from the more equidimensional three-fingered hand of earlier coelurosaurs like Compsognathus. Recent discoveries, such as the 2023 non-paravian maniraptoran Migmanychion laiyang with its mixed therizinosauroid-oviroptorosaur hand features, further illustrate this morphological diversity.^[4]^[5] Manual unguals are enlarged, compressed, and strongly recurved, with prominent flexor tubercles, adaptations that enhance grasping ability compared to the straighter claws of outgroup theropods. In the pedal region, many maniraptorans, particularly within Paraves, possess an enlarged second pedal ungual forming a sickle-like claw, which is hypertrophied relative to other digits and absent in broader tetanurans.^[6] Additional skeletal features include a retroverted pubis, oriented posteroventrally with a reduced anterior foot, which shifts the pelvic structure for improved balance and differs from the anteroventrally directed pubis of most non-maniraptoran coelurosaurs.^[4] The thoracic ribs bear uncinate processes, bony projections that extend caudally from the midpoint of the rib shaft, enhancing respiratory mechanics by increasing leverage for costal movements; these processes are homologous across Maniraptora and absent in outgroup theropods like Allosaurus, where ribs lack such extensions.^[7] In some taxa, such as paravians, asymmetrical feathers further extend these traits, contributing to aerodynamic functions, though detailed integumentary aspects are elaborated elsewhere.^[4]

Integument and flight adaptations

Maniraptorans possessed a diverse array of integumentary structures, primarily feathers, preserved exceptionally in fossils from the Early Cretaceous Jehol Biota of Liaoning Province, China.^[8] These include simple filamentous structures in basal forms, such as the broad, unbranched filaments observed in the therizinosaur Beipiaosaurus inexpectus, which measured up to 150 mm long and 3 mm wide and covered the head, neck, and tail.^[9] More derived maniraptorans, including dromaeosaurids and troodontids, exhibited pennaceous feathers with vaned structures, as seen in Sinornithosaurus and the troodontid Jianianhualong, where asymmetrical vanes on tail feathers suggest aerodynamic refinement. In avialans, these evolved into complex vaned flight feathers with distinct primaries and secondaries, enabling precise control during locomotion. The progression from simple filaments to pennaceous feathers across Maniraptora reflects an early diversification of integumentary coverings prior to the origin of flight. Filamentous protofeathers in basal taxa likely served foundational roles, while pennaceous forms proliferated on the limbs and tail in paravians, as evidenced by the four-winged configuration in microraptorines like Microraptor gui, where long, asymmetrical pennaceous feathers extended from all four limbs.^[8] This distribution, with feathers up to 20 cm on the legs, indicates a tetrapteryx (four-winged) stage in evolution, bridging gliding and powered flight.^[8] In basal avialans such as Archaeopteryx, vaned feathers formed high-aspect-ratio wings (approximately 5–6), contrasting with the lower ratios (around 3.7) in microraptorine biplane-like structures.^[10] Flight adaptations in maniraptorans evolved through incremental stages, with microraptorines representing advanced gliding capabilities. Microraptor achieved stable glides with a lift-to-drag ratio of up to 4.7:1 in a legs-down posture, supported by a wing loading of approximately 50 N/m²—comparable to modern birds of similar mass—and enabled medium-distance aerial descent from heights of 20–30 m.^[11] This configuration optimized high-lift, high-drag performance for maneuverability in forested environments, rather than efficient long-distance travel. In avialans, these adaptations advanced to powered flight, with taxa like Anchiornis and early ornithuromorphs exhibiting wing loadings below 25 N/m² and sufficient specific lift (exceeding 9.8 N/kg) to sustain flapping, marking the threshold for active aerial propulsion.^[12] Aspect ratios increased in avialans to enhance efficiency, allowing sustained flight absent in non-avialan relatives. Beyond aerial functions, maniraptoran feathers facilitated brooding and thermoregulation, as inferred from nesting fossils and integumentary impressions. Oviraptorids, such as Citipati osmolskae, brooded eggs in an avian-like posture, with feathers likely aiding insulation to maintain nest temperatures, similar to modern birds; this is supported by pennaceous feather impressions in related caudipterygids from Liaoning.^[13] Filamentous and pennaceous structures in small-bodied maniraptorans, including troodontids and dromaeosaurids, provided thermal insulation in cooler Early Cretaceous climates, with broad filaments in basal forms enhancing body coverage for heat retention.^[9] These non-aerial roles underscore the multifunctional origins of feathers, predating flight adaptations.^[14]

Classification

Phylogenetic relationships

Maniraptora is a clade of coelurosaurian theropod dinosaurs defined as all theropods more closely related to Passer domesticus than to Ornithomimus velox, as established by the foundational phylogenetic framework of Gauthier in 1986.^[15] This node-based definition emphasizes the shared derived traits among advanced maniraptorans, positioning Maniraptora as a key branch within the broader radiation of Coelurosauria, encompassing taxa with enhanced manual dexterity and precursors to avian flight adaptations.^[1] Within Coelurosauria, the position of Maniraptora varies across phylogenetic analyses, often emerging as sister to Ornithomimosauria in matrix-based studies that recover a topology of (Tyrannosauroidea (Ornithomimosauria + Maniraptora)).^[1] Alternative reconstructions, such as those incorporating expanded character sets for oviraptorosaurs and therizinosauroids, place core Maniraptora (Paraves) as sister to Oviraptorosauria, with Therizinosauroidea branching basally within the clade.^[16] These discrepancies highlight the influence of taxon sampling and character scoring on resolving deep coelurosaurian divergences, with Maniraptora consistently recognized as a monophyletic group more derived than tyrannosauroids but inclusive of the avian lineage. Key debates in maniraptoran phylogeny center on internal branching patterns, particularly the monophyly of Deinonychosauria, traditionally comprising Dromaeosauridae and Troodontidae as successive outgroups to Avialae.^[16] Some analyses support this grouping based on shared features like the arctometatarsal foot and sickle claw, but others recover Troodontidae as closer to Avialae than to Dromaeosauridae, potentially rendering Deinonychosauria paraphyletic and emphasizing rapid evolutionary rates at the base of Paraves.^[6] Similarly, the placement of Scansoriopterygidae remains contentious, with cladistic studies variably positioning it as a basal avialan due to elongated manual elements or as a basal paravian outside Deinonychosauria, reflecting uncertainties in scoring integumentary and arboreal adaptations. These debates underscore the need for integrated datasets combining osteological and soft-tissue evidence to stabilize paravian relationships.

Major subgroups and key taxa

Maniraptora encompasses several major subgroups, including Therizinosauria, Alvarezsauria, Oviraptorosauria, and Paraves.^[3] Therizinosauria comprises herbivorous or omnivorous theropods characterized by pot-bellied bodies, long necks, and massive claws on reduced forelimbs. Key taxa include Therizinosaurus cheloniformis from the Late Cretaceous of Mongolia, known for its enormous scythe-like claws up to 1 meter long, and Nothronychus mckinleyi from the Early Cretaceous of North America, estimated at 4.5 meters in length.^[3] Alvarezsauria includes small, specialized theropods with highly reduced forelimbs ending in a single large claw, likely adapted for digging or insectivory. Representative taxa are Mononykus olecranus from the Late Cretaceous of Mongolia, about 0.6 meters long, and Shuvuuia deserti, a feathered form from the same region measuring around 0.5 meters.^[3] Oviraptorosauria features crested skulls and short tails, with diets ranging from omnivorous to herbivorous, and evidence of brooding behavior. Notable species include Oviraptor philoceratops from the Late Cretaceous Gobi Desert, approximately 1.5 meters long, and the giant Gigantoraptor erlianensis from the Early Cretaceous of China, reaching up to 8 meters in length.^[1]^[3] Paraves, derived from Latin para- ("beside") and aves ("birds"), comprises small-bodied, feathered theropods that exhibit advanced adaptations potentially linked to flight capability, with body lengths typically ranging from crow-sized basal forms around 0.5 meters, such as Archaeopteryx, to larger species up to 2 meters or more.^[3] Dromaeosauridae, known as "running lizards" from Greek dromaios ("running") and sauros ("lizard"), form a prominent subfamily within Paraves characterized by a hyperextensible sickle-shaped claw on the second pedal digit. Key taxa include Velociraptor mongoliensis, a Late Cretaceous dromaeosaurid from the Gobi Desert measuring approximately 2 meters in length, and Deinonychus antirrhopus, a North American species from the Early Cretaceous reaching up to 3.4 meters long and weighing around 73 kilograms.^[1] Another exemplar is Microraptor gui, a basal dromaeosaurid from the Early Cretaceous Jehol Biota of China, notable for its four-winged gliding adaptations and a total length of about 1 meter.^[3] Troodontidae, featuring relatively large brains and binocular vision, includes taxa like Mei long, a small Early Cretaceous troodontid from China's Yixian Formation measuring roughly 0.5 meters in length, and Zanabazar junior, a Late Cretaceous troodontid from Mongolia estimated at 2.3 meters long.^[3] These dinosaurs highlight the clade's range from pigeon-sized to deer-sized individuals.^[1] Avialae, the subgroup containing modern birds and their closest extinct relatives, features basal taxa such as Archaeopteryx lithographica, a Late Jurassic specimen from Germany about 0.5 meters long with a mix of reptilian and avian traits, and Rahonavis ostromi, a Late Cretaceous avialan from Madagascar known from partial remains suggesting a size similar to a turkey.^[3] Scansoriopterygids, sometimes allied with Avialae or Oviraptorosauria, are exemplified by Yi qi, a Middle Jurassic taxon from China with unusual membranous wings supported by an elongated styliform element on the wrist, reaching approximately 0.5 meters in length.^[3] The diversity of Maniraptora includes over 100 described non-avian species across its subgroups, underscoring its evolutionary success as the most speciose theropod clade.^[3] The Early Cretaceous Jehol Biota in northeastern China has been particularly instrumental in revealing this diversity, providing exceptionally preserved fossils of feathered maniraptorans like Microraptor, Caudipteryx, and Sinovenator that illuminate integumentary and locomotor variations.^[17]

Evolutionary history

Timeline and origins

The origins of Maniraptora trace back to the Middle-Late Jurassic period, approximately 165–160 million years ago, marking the emergence of this clade within Coelurosauria. The earliest potential records come from the Tiaojishan Formation in northeastern China, where fossils of basal paravians such as Anchiornis huxleyi provide evidence of early maniraptoran diversification during the Oxfordian stage.^[18]^[19] These specimens, dated to around 160 Ma, indicate that key maniraptoran innovations, including pennaceous feathers and cursorial adaptations, had already evolved by this time.^[20] Recent phylogenetic analyses, including machine learning approaches, have confirmed an early radiation of maniraptorans by the Middle Jurassic, with ongoing refinements to relationships within Paraves.^[21] A significant radiation occurred in the Late Jurassic, around 150 Ma, with the appearance of avialans such as Archaeopteryx lithographica from the Solnhofen Limestone in Germany. This event highlights the rapid evolution of flight-related traits within Paraves, coinciding with the Tithonian stage and representing one of the earliest documented instances of possible flight capabilities in dinosaurs.^[22]^[23] Maniraptora underwent further diversification during the Cretaceous, particularly among dromaeosaurids, which peaked in abundance and variety during the Aptian-Albian stages (approximately 125–100 Ma). This Early Cretaceous radiation is evidenced by numerous taxa from formations like the Yixian and Jiufotang in China and the Cloverly Formation in North America, reflecting adaptive expansions into diverse ecological niches.^[24]^[25] Oviraptorosaurs and troodontids also proliferated across Laurasia during this interval, contributing to the clade's overall morphological and behavioral diversity.^[26] The evolutionary timeline of Maniraptora culminated in the extinction patterns at the Cretaceous-Paleogene (K-Pg) boundary, 66 million years ago. While non-avian maniraptorans, including dromaeosaurids, troodontids, and oviraptorosaurs, perished alongside other non-avian dinosaurs, the avialan lineage (modern birds) survived the mass extinction event, likely due to small body size, flight capabilities, and ecological versatility.^[27]^[28] This selective survival underscores the resilience of Avialae through the end-Cretaceous crisis.^[29]

Biogeography and diversity patterns

Maniraptoran fossils are predominantly known from Laurasian landmasses, with major discoveries concentrated in East Asia, particularly the Early Cretaceous Jehol Biota of northeastern China, which has yielded exceptionally preserved specimens including feathered taxa such as Microraptor and Sinornithosaurus.^[30] Other key Laurasian sites include the Late Cretaceous Gobi Desert formations of Mongolia, home to iconic dromaeosaurids like Velociraptor, and various North American deposits such as the Hell Creek and Judith River Formations, which have produced diverse paravian remains.^[31] In contrast, Gondwanan records are sparser but significant, exemplified by Austroraptor cabazai, a large unenlagiine dromaeosaurid from the Late Cretaceous Allen Formation in Patagonia, Argentina, highlighting a distinct southern lineage of maniraptorans adapted to Gondwanan ecosystems.^[32] An isolated troodontid tooth from the Maastrichtian Kallamedu Formation in southern India further indicates rare Gondwanan occurrences, possibly resulting from Laurasian dispersal or an underrecognized southern radiation.^[33] Diversity patterns of maniraptorans exhibit a clear temporal trajectory across the Mesozoic, beginning with low representation in the Jurassic, where fossils are scarce and typically limited to isolated teeth or fragmentary remains, suggesting limited diversification prior to the Cretaceous.^[31] This shifted dramatically in the Early Cretaceous, marked by a peak in species richness within the Jehol Biota, which preserves at least 13 non-avian maniraptoran species across 12 genera, alongside numerous early avialans, totaling over 20 maniraptoran taxa in this exceptional lagerstätte.^[34] By the Late Cretaceous, diversity appears to have declined, aligning with broader non-avian dinosaur trends driven by global cooling and reduced speciation rates, though ecological disparity in dental morphology remained stable, indicating persistent functional diversity among surviving lineages.^[27]^[29] Biogeographic provincialism is evident in maniraptoran distributions, with troodontids showing strong Asian endemism through an endemic radiation that includes multiple genera such as Xixiasaurus, Byronosaurus, and Urbacodon, concentrated in East Asian formations and rarely extending beyond Laurasia.^[35] North America hosted hotspots for dromaeosaurids, with diverse eudromaeosaur taxa like Dromaeosaurus and Saurornitholestes in western formations, reflecting repeated faunal turnovers.^[36] Intercontinental dispersal, particularly via the Beringian land bridge, facilitated exchanges between Asia and North America, as evidenced by a juvenile dromaeosaurid specimen from the Prince Creek Formation in Arctic Alaska, the first non-dental Arctic record of the clade and underscoring Beringia's role in Late Cretaceous maniraptoran migrations.^[37]

Paleobiology

Locomotion and ecology

Maniraptorans displayed a range of locomotor adaptations suited to diverse terrestrial and arboreal environments, reflecting their ecological versatility within the clade. Dromaeosaurids, such as Deinonychus antirrhopus, exhibited cursorial features including elongated hindlimbs and a reduced fibula, enabling agile terrestrial locomotion for pursuing prey on open ground. These adaptations prioritized burst speed and maneuverability over sustained endurance, distinguishing dromaeosaurids from more specialized cursorial theropods like ornithomimids.^[38] In contrast, scansoriopterygids represented arboreal specialists among maniraptorans, with elongated manual digits, strongly recurved claws, and flexible forelimbs adapted for climbing and navigating tree branches. Fossil evidence from taxa like Scansoriopteryx heilmanni indicates scansorial capabilities, allowing these small dinosaurs to exploit forested habitats for foraging and predator avoidance. Similarly, Epidexipteryx hui, a diminutive scansoriopterygid, likely engaged in scansorial behaviors, using its grasping feet and hands to ascend trunks and branches, as inferred from its pedal and manual morphology consistent with arboreal perching and climbing.^[39] These features suggest an ecological niche focused on vertical mobility in Jurassic woodlands. Therizinosaurs, such as Therizinosaurus, adopted a quadrupedal or facultative bipedal gait for foraging in vegetation, with robust limbs supporting their large body size.^[40] Alvarezsaurids, like Mononykus, had short, powerful forelimbs suited for digging burrows, indicating a subterranean ecology for accessing insects.^[41] Ecological interactions among maniraptorans included social behaviors that enhanced habitat exploitation. Trackways from Early Cretaceous deposits in China preserve impressions of multiple deinonychosaurs moving in unison, providing evidence for gregarious locomotion and possible pack hunting strategies to tackle larger prey or coordinate territorial defense.^[42] Such group dynamics likely allowed dromaeosaurids to occupy predatory niches in dynamic ecosystems, balancing solitary pursuits with cooperative movements. Respiratory enhancements in maniraptorans supported their active lifestyles through avian-like ventilatory mechanics. Uncinate processes—bony projections on the ribs—were present in taxa like Velociraptor and basal avialans, functioning to increase the mechanical advantage of rib and sternal movements during breathing. These structures facilitated efficient airflow through a lung-air sac system, enabling high metabolic rates for sustained locomotion independent of flight capabilities. This respiratory efficiency underscores the physiological underpinnings of maniraptoran ecological success across varied habitats.

Diet and feeding strategies

Maniraptorans exhibited predominantly carnivorous diets, as inferred from their recurved, serrated teeth adapted for piercing and tearing flesh. In dromaeosaurids, ziphodont teeth—characterized by flattened crowns with fine denticles—facilitated a puncture-and-pull feeding mechanism, where the teeth embedded into prey during biting and created parallel scratches upon withdrawal, ideal for dismembering struggling victims.^[43]^[44] Biomechanical models indicate that small dromaeosaurids, such as those comparable to Microraptor, generated bite forces around 90–200 N, sufficient for subduing small vertebrates without risking tooth fracture.^[43]^[45] Dietary variations occurred across maniraptoran subgroups, reflecting ecological diversification. Troodontids likely incorporated insectivory, supported by their finely serrated teeth suited for grasping small, hard-bodied invertebrates and a high encephalization quotient suggesting advanced prey detection and manipulation strategies.^[46] Oviraptorosaurs showed adaptations for omnivory, with robust, toothless beaks capable of crushing seeds, nuts, or small animals, diverging from the ancestral theropod carnivory.^[47] Therizinosaurs were primarily herbivorous, using their large claws to pull down branches and leaf-shaped teeth for grinding plant matter.^[40] Alvarezsaurids specialized in myrmecophagy or termitophagy, employing their tubular snouts and single strong claw for excavating ant or termite nests.^[41] Among avialans, some early forms engaged in frugivory, as evidenced by gut contents in Jeholornis containing seeds from gymnosperms, indicating seasonal fruit consumption and potential seed dispersal roles.^[48] Hunting strategies in maniraptorans emphasized prey restraint and opportunistic predation. Dromaeosaurids employed their enlarged sickle-shaped claws on pedal digit II to immobilize prey, pinning it against the body or substrate before delivering bites, a tactic inferred from biomechanical analyses of claw curvature and forelimb strength.^[49] Direct evidence from fossil gut contents, such as lizards preserved in Microraptor specimens, confirms a generalist carnivorous diet targeting small reptiles, alongside fish, birds, and mammals, underscoring versatile ambush or pursuit hunting in arboreal or terrestrial settings.^[50]^[51]

Reproduction and ontogeny

Maniraptorans displayed advanced reproductive strategies, including brooding behaviors documented in oviraptorid fossils. In oviraptorids such as Citipati osmolskae, adults were preserved in a brooding posture atop nests, with forelimbs extended to cover the clutch and hindlimbs positioned to shield the eggs, mirroring modern avian incubation.^[52] These nests typically featured eggs arranged in concentric rings of up to three layers, with clutch sizes ranging from 6 to 22 eggs in adult-associated specimens, often partially buried in sediment to stabilize the structure.^[53] One exceptional fossil from the Upper Cretaceous Nanxiong Formation preserves an oviraptorid adult in brooding posture over a clutch of at least 24 eggs containing late-stage embryos, indicating active incubation at temperatures of 30–38 °C and asynchronous hatching where embryos developed at varying rates.^[53] Ontogenetic development in maniraptorans involved rapid growth phases, particularly in smaller taxa, enabling quick maturation to reproductive age. For instance, troodontids and microraptorines exhibited accelerated growth rates, with juveniles potentially increasing from hatchling masses around 100 g to adult sizes exceeding 1 kg within months through high metabolic efficiency and continuous bone deposition. Sexual dimorphism emerged during ontogeny, especially in feather structures among avialans, where post-juvenile molts produced sexually distinct plumage patterns, such as elongated tail feathers in confuciusornithiforms and enantiornithines, likely for display during breeding.^[54] These shifts highlight how integumentary features, including feathers used in brooding, transitioned from juvenile insulation to adult reproductive signaling.^[54] Evidence for parental care derives from nest sites and embryo fossils, suggesting biparental or paternal investment in non-avialan maniraptorans. Oviraptorid associations imply extended nest attendance, with adults potentially remaining post-hatching to protect precocial young, as inferred from perinate remains near nests.^[55] In avialans, fossil embryos within eggs exhibit bird-like tucking postures, and nest structures indicate high reproductive output through larger clutches or multiple breeding attempts, facilitating population resilience in early birds.^[55] Paternal care, ancestral to modern birds, is supported by troodontid and oviraptorid fossils showing males in brooding roles, predating avian divergence.^[56]

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[PDF] Machine learning confirms new records of maniraptoran theropods ...
Key words: Maniraptora, Theropoda, Middle Jurassic, teeth, machine learning. MANIRAPTORA is a diverse and speciose clade of thero- pod dinosaurs that includes ...
[30]
A bizarre Cretaceous theropod dinosaur from Patagonia and the ...
Discovery of Austroraptor has important consequences in the understanding of the evolution of southern dromaeosaurids, and sheds new light about the ...
[31]
A troodontid dinosaur from the latest Cretaceous of India - Nature
Apr 16, 2013 · This small-bodied maniraptoran dinosaur is an unexpected and distinctly 'Laurasian' component of an otherwise typical 'Gondwanan' tetrapod ...
[32]
[PDF] Vertebrate diversity of the Jehol Biota as compared with other ...
The Jehol Biota has at least 121 genera and 142 species of vertebrates, including 33 genera and 39 species of birds, and 30 genera and 35 species of dinosaurs.
[33]
A new troodontid theropod from the Late Cretaceous of central ...
Byronosaurus, Urbacodon, and Xixiasaurus may form a new clade, suggesting an endemic radiation of troodontids across Asia, including multiple taxa without ...
[34]
Dinosaurs in decline tens of millions of years before their final ...
Apr 18, 2016 · On a broader scale, the fact that dinosaurian taxic diversity curves appear to be stable after ghost lineages or sampling biases are taken ...
[35]
The first juvenile dromaeosaurid (Dinosauria: Theropoda) from ...
Jul 8, 2020 · This is the first confirmed non-dental fossil specimen from a member of Dromaeosauridae in the Arctic, expanding on the role of Beringia as a dispersal route ...
[36]
Predictive simulations of running gait reveal a critical dynamic role ...
Sep 22, 2021 · The OCP converged in <5 min, and we obtained a maximum speed of 6.65 m/s, comparable to previous static-based estimates and empirical scaling ...
[37]
An approach to scoring cursorial limb proportions in carnivorous ...
Jan 27, 2016 · In this paper, we do not estimate absolute or relative maximum running speeds, but rather quantify and compare theropod limb proportions to ...
[38]
Scansorial and aerial ability in Scansoriopterygidae and basal ...
Dec 14, 2020 · All known scansoriopterygids were capable of scansorial locomotion and gliding, but not active flight, suggesting that the most recent common ancestor of ...
[39]
Jurassic Park May Have Been Right—Some Dinosaurs Hunted in ...
Jan 7, 2015 · The film inspired paleontologists to discover the truth about dinos, including whether raptors were social hunters.Missing: maniraptora | Show results with:maniraptora
[40]
https://www.nature.com/articles/s41598-020-78596-4
[41]
A Functional Explanation for Denticulation in Theropod Dinosaur ...
Aug 26, 2009 · The serrated, or denticulated, ziphodont teeth of theropod dinosaurs display variability in their extent of denticulation.
[42]
Estimating bite force in extinct dinosaurs using phylogenetically ...
Jul 12, 2022 · My estimated FBite of 706N is in line with those of a similarly sized dromaeosaur Dromaeosaurus at 885N (WSk = 103 mm), and a similarly sized ...
[43]
[PDF] DENTICLE MORPHOMETRICS AND A POSSIBLY OMNIVOROUS ...
VARRICCHIO (1997), for example, postulated a pri- marily insectivorous diet for troodontids. However, given the morphometric similarities be- tween the teeth of ...Missing: insectivory | Show results with:insectivory
[44]
Functional anatomy of a giant toothless mandible from a bird-like ...
Nov 24, 2017 · The Oviraptorosauria are a group of theropod dinosaurs that diverged from the typical carnivorous theropod diet.
[45]
Earliest evidence for fruit consumption and potential seed dispersal ...
Aug 16, 2022 · Frugivorous birds play an important role in seed dispersal today. However, evidence of fruit consumption in early birds from outside the crown- ...
[46]
Testing the function of dromaeosaurid (Dinosauria, Theropoda ... - NIH
Aug 28, 2019 · A musculoskeletal model of the hindlimb and pes of Deinonychus was developed, and mathematical optimization was used to assess the factors that maximize ...
[47]
Microraptor with Ingested Lizard Suggests Non-specialized ...
Jul 22, 2019 · However, Microraptor preserves only stomach contents, whereas Anchiornis preserves only gastric pellets. Given the large amount of data ...
[48]
Generalist diet of Microraptor zhaoianus included mammals
This adds to the known diversity of diet for this genus, which also consumed birds, fish, and lizards. Previous interpretations that Microraptor was an arboreal ...Missing: gut contents
[49]
A Second Specimen of Citipati Osmolskae Associated With a Nest of ...
Apr 26, 2018 · Here we report on a second nesting oviraptorid specimen (IGM 100/1004) sitting in a brooding position atop a nest of eggs from Ukhaa Tolgod, Omnogov, Mongolia.
[50]
An oviraptorid preserved atop an embryo-bearing egg clutch sheds ...
May 15, 2021 · Here we report the first non-avialan dinosaur fossil known to preserve an adult skeleton atop an egg clutch that contains embryonic remains.
[51]
Development, Regeneration, and Evolution of Feathers - PMC
At puberty they produce juvenal feathers, and during the reproductive stage they form sexually dimorphic feather types. These different feathers are produced ...
[52]
The reproductive biology of oviraptorosaurs: a synthesis
A recent taphonomic study concluded that all oviraptorid egg clutches from the Nanxiong Group preserve their clutch architecture and pattern well (He et al.
[53]
Avian paternal care had dinosaur origin - PubMed
Paternal care in both troodontids and oviraptorids indicates that this care system evolved before the emergence of birds and represents birds' ancestral ...Missing: maniraptora avialans