[Paleontology • 2022] Earliest Evidence for Fruit Consumption and Potential Seed Dispersal by Birds

  

in Hu, Wang, McDonald, et al., 2022. 

DOI: 10.7554/eLife.74751

Abstract

The Early Cretaceous diversification of birds was a major event in the history of terrestrial ecosystems, occurring during the earliest phase of the Cretaceous Terrestrial Revolution, long before the origin of the bird crown-group. Frugivorous birds play an important role in seed dispersal today. However, evidence of fruit consumption in early birds from outside the crown-group has been lacking. Jeholornis is one of the earliest-diverging birds, only slightly more crownward than Archaeopteryx, but its cranial anatomy has been poorly understood, limiting trophic information which may be gleaned from the skull. Originally hypothesised to be granivorous based on seeds preserved as gut contents, this interpretation has become controversial. We conducted high-resolution synchrotron tomography on an exquisitely preserved new skull of Jeholornis, revealing remarkable cranial plesiomorphies combined with a specialised rostrum. We use this to provide a near-complete cranial reconstruction of Jeholornis, and exclude the possibility that Jeholornis was granivorous, based on morphometric analyses of the mandible (3D) and cranium (2D), and comparisons with the 3D alimentary contents of extant birds. We show that Jeholornis provides the earliest evidence for fruit consumption in birds, and indicates that birds may have been recruited for seed dispersal during the earliest stages of the avian radiation. As mobile seed dispersers, early frugivorous birds could have expanded the scope for biotic dispersal in plants, and might therefore explain, at least in part, the subsequent evolutionary expansion of fruits, indicating a potential role of bird–plant interactions in the Cretaceous Terrestrial Revolution.

Seeds preserved in the abdominal area of selected Jeholornis prima specimens.
(A) IVPP V13274 (holotype). (B) STM 2–41.
(C) Close-up image of seeds in IVPP V13274 (A). (D) Gastrolith mass in J. prima STM 2–15.

 Photos in A–D followed figures in O’Connor et al., 2018. 

Scale bars equal 5 mm.

 Han Hu, Yan Wang, Paul G. McDonald, Stephen Wroe, Jingmai K. O'Connor, Alexander Bjarnason, Joseph J Bevitt, Xuwei Yin, Xiaoting Zheng, et al. 2022. Earliest Evidence for Fruit Consumption and Potential Seed Dispersal by Birds. eLife 11:e74751. DOI: 10.7554/eLife.74751

 phys.org/news/2022-08-early-bird-fruit-fossil-earliest.html

[Paleontology • 2021] Nuclear Preservation in the Cartilage of the Jehol Dinosaur Caudipteryx

in Zheng, Bailleul, ... et Zhou, 2021. 

 DOI: 10.1038/s42003-021-02627-8

Abstract

Previous findings on dinosaur cartilage material from the Late Cretaceous of Montana suggested that cartilage is a vertebrate tissue with unique characteristics that favor nuclear preservation. Here, we analyze additional dinosaur cartilage in Caudipteryx (STM4-3) from the Early Cretaceous Jehol biota of Northeast China. The cartilage fragment is highly diagenetically altered when observed in ground-sections but shows exquisite preservation after demineralization. It reveals transparent, alumino-silicified chondrocytes and brown, ironized chondrocytes. The histochemical stain Hematoxylin and Eosin (that stains the nucleus and cytoplasm in extant cells) was applied to both the demineralized cartilage of Caudipteryx and that of a chicken. The two specimens reacted identically, and one dinosaur chondrocyte revealed a nucleus with fossilized threads of chromatin. This is the second example of fossilized chromatin threads in a vertebrate material. These data show that some of the original nuclear biochemistry is preserved in this dinosaur cartilage material and further support the hypothesis that cartilage is very prone to nuclear fossilization and a perfect candidate to further understand DNA preservation in deep time.

Photograph and line drawing of Caudipteryx STM4-3.
 a Photograph of the full slab. b Close-up on the right femur showing the extracted fragment outlined in yellow. c Line drawing of the specimen showing bones in light gray, the mass of gastroliths inside the body in pale gray and integument imprints in dark gray.

cav, caudal vertebrae; cev, cervical vertebrae; Demin. P-S, demineralization and paraffin sections; fi, fibula; G-S SEM, Ground-sections and scanning electron microscopy; il, ilium; is, ischium; l co, left coracoid; l de, left dentary; l fe, left femur; l hu, left humerus; l ra, left radius; l tb, left tibiotarsus; l ul, left ulna; ma, maxilla; mtII, metatarsal II; mtIV, metatarsal IV; pu, pubis; r co, right coracoid; r de, right dentary; r fe, right femur; r hu, right humerus; r ra, right radius; r sc, right scapula; r tb, right tibiotarsus; r ul, right ulna; sk, skull elements; TEM, transmission electron microscopy.

Reconstruction of the Jehol Biota and the well-preserved specimen of Caudipteryx.

Illustration: ZHENG Qiuyang

Xiaoting Zheng, Alida M. Bailleul, Zhiheng Li, Xiaoli Wang and Zhonghe Zhou. 2021. Nuclear Preservation in the Cartilage of the Jehol Dinosaur Caudipteryx. Communications Biology. 4: 1125. DOI: 10.1038/s42003-021-02627-8

Organic molecule remnants found in nuclei of ancient dinosaur cells

 eurekalert.org/news-releases/929480

[Paleontology • 2020] Ubirajara jubatus • A Maned Theropod Dinosaur (Theropoda: Compsognathidae) from Gondwana with Elaborate Integumentary Structures

Ubirajara jubatus 

 Smyth, Martill, Frey, Rivera-Sylva & Lenz, 2020 

DOI: 10.1016/j.cretres.2020.104686  

Illustration: Bob Nicholls twitter.com/PaleoCreations 

 Abstract

Discoveries of dinosaurs with integumentary structures over the last few decades have revolutionised our understanding of the phylogenetic relationships between birds and dinosaurs as well as the origin and evolution of feathers. A remarkable number of dinosaurs have been discovered with a diverse range of preserved integumentary structures. Several of these dinosaurs are adorned with elaborate integumentary structures that have been linked to behaviours including thermoregulation, egg incubation, and sexual display. Among Theropoda, such elaborate structures have only been previously recorded within Maniraptoriformes. However, elaborate monofilamentous structures are also present in some small ornithischians. The majority of theropods preserving integumental structures come from the Upper Jurassic and Lower Cretaceous of China or the Upper Jurassic of southern Germany, and all are of Laurasian origin. Herein, we describe a new genus and species of compsognathid theropod from the Lower Cretaceous (Aptian) Crato Formation of Northeast Brazil, representing the first Gondwanan non-avian theropod with preserved filamentous integumentary structures. It is also the first non-maniraptoran possessing elaborate integumentary structures that were most likely used for display. These include slender monofilaments associated with the base of the neck, increasing in length along the dorsal thoracic region where they form an impressive mane, as well as a pair of elongate, ribbon-like structures likely emerging from the shoulder. Such elaborate integumentary structures are hitherto unknown in any other dinosaur, although superficially similar elongate display feathers emerge from the carpal region of the male standardwing bird-of-paradise (Semioptera wallacii).

Keywords: Crato Formation, Lower Cretaceous, Dinosauria, Compsognathidae, Ubirajara jubatus, Integumentary structures

Ubirajara jubatus (SMNK PAL 29241):
A, Interpretative line drawing showing combined slab and mirrored counter slab.
B, Reconstruction showing preserved skeletal elements in white and integumentary structures in brown, with missing elements in grey. Elaborate display structures reconstructed as emanating from the scapular region in yellow.

DINOSAURIA Owen 1842 

THEROPODA Marsh 1881 

COELUROSAURIA von Huene 1914 

COMPSOGNATHIDAE Cope 1871 

UBIRAJARA gen. nov.

Ubirajara jubatus gen. et sp. nov. 

Etymology. Genus, Ubirajara, is a traditional Tupi name meaning lord of the spear, in reference to the stiffened, elongate integumentary structures associated with the specimen. The specific epithet jubatus is from the Latin, meaning maned or crested.  

Ubirajara jubatus: elaborate integumentary structures.
A, Mane of slender monofilamentous integumentary structures.
B, Paired hypertrophied broad monofilamentous integumentary structures.

Abbreviations: BMFIs, broad monofilamentous integuments; ce, cervical vertebra; cer, cervical rib; d, dorsal vertebra; ga, gastralia; rco, right coracoid; rsc, right scapula; s, sacral vertebra; SMFIs, slender monofilamentous integuments. Scale bars ¼ 20 mm

 

 Robert S.H. Smyth, David M. Martill, Eberhard Frey, Héctor E. Rivera-Sylva and Norbert Lenz. 2020. A Maned Theropod Dinosaur from Gondwana with Elaborate Integumentary Structures. Cretaceous Research.  In Press. DOI: 10.1016/j.cretres.2020.104686

 twitter.com/PaleoCreations/status/1338264588861779969

      

[Paleontology • 2020] Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds

 

Highlights

• Support Deinonychosauria as sister taxon to birds and Anchiornithinae as early birds

• Powered flight potential evolved ≥3 times: once in birds and twice in dromaeosaurids

• Many ancestors of bird relatives neared thresholds of powered flight potential

• Broad experimentation with wing-assisted locomotion before theropod flight evolved

Summary

Uncertainties in the phylogeny of birds (Avialae) and their closest relatives have impeded deeper understanding of early theropod flight. To help address this, we produced an updated evolutionary hypothesis through an automated analysis of the Theropod Working Group (TWiG) coelurosaurian phylogenetic data matrix. Our larger, more resolved, and better-evaluated TWiG-based hypothesis supports the grouping of dromaeosaurids + troodontids (Deinonychosauria) as the sister taxon to birds (Paraves) and the recovery of Anchiornithinae as the earliest diverging birds. Although the phylogeny will continue developing, our current results provide a pertinent opportunity to evaluate what we know about early theropod flight. With our results and available data for vaned feathered pennaraptorans, we estimate the potential for powered flight among early birds and their closest relatives. We did this by using an ancestral state reconstruction analysis calculating maximum and minimum estimates of two proxies of powered flight potential—wing loading and specific lift. These results confirm powered flight potential in early birds but its rarity among the ancestors of the closest avialan relatives (select unenlagiine and microraptorine dromaeosaurids). For the first time, we find a broad range of these ancestors neared the wing loading and specific lift thresholds indicative of powered flight potential. This suggests there was greater experimentation with wing-assisted locomotion before theropod flight evolved than previously appreciated. This study adds invaluable support for multiple origins of powered flight potential in theropods (≥3 times), which we now know was from ancestors already nearing associated thresholds, and provides a framework for its further study.

 

Keywords: flight origins, powered flight, early birds, paravians, feathered dinosaurs, wing loading, specific lift, coelurosaurs, theropods, phylogeny

 Rui Pei, Michael Pittman, Pablo A. Goloboff, T. Alexander Dececchi, Michael B. Habib, Thomas G. Kaye, Hans C.E. Larsson, Mark A. Norell, Stephen L. Brusatte and Xing Xu. 2020. Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds. Current Biology. In Press. DOI: 10.1016/j.cub.2020.06.105

twitter.com/PalaeoPittman/status/1291535509596979200

[Paleontology • 2019] A Polar Dinosaur Feather Assemblage from Australia

Australian feathered polar dinosaur.

in Kundrát, Rich, Lindgren, et al., 2019. 

 DOI: 10.1016/j.gr.2019.10.004 

 Illustration: Peter Trusler 

Highlights: 

• Fossil feathers from the Koonwarra Fossil Bed in southeastern Australia record the first demonstrable dinosaur (including birds) integumentary structures described from the Mesozoic polar regions.

• This diverse range of non-avian theropod (paravian) and bird feathers more than doubles the number of Mesozoic fossil feather specimens and morphologies recovered from the Gondwanan landmasses to date.

• Possible traces of eumelanosomes imply original dark colouration and patterning. Some of the geologically oldest barbicel-like structures also evince advanced avian-grade flight feather morphologies in the Early Cretaceous.

ABSTRACT

Exceptionally preserved Mesozoic feathered dinosaur fossils (including birds) are famous, but recognized from only very few localities worldwide, and are especially rare in the Southern Hemisphere. Here we report an assemblage of non-avian and avian dinosaur feathers from an Early Cretaceous polar (around 70°S) environment in what is now southeastern Australia. The recovered remains incorporate small (10–30 mm long) basal paravian-like tufted body feathers, open-vaned contour feathers, and asymmetrical bird-like wing feathers that possess high-angled barbs with possible remnants of barbicels — amongst the geologically oldest observed to date. Such morphological diversity augments scant skeletal evidence for a range of insulated non-avian theropods and birds inhabiting extreme southern high-latitude settings during the Mesozoic. Although some of these fossil feathers exhibit what may be residual patterning, most are uniformly toned and preserve rod-shaped microbodies, as well as densely-packed microbody imprints on the barbules that are structurally consistent with eumelanosomes. Geochemical analysis detected no identifiable residual biomolecules, which we suspect were lost via hydrolysis and oxidization during diagenesis and weathering. Nevertheless, an originally dark pigmentation can be reasonably inferred from these melanic traces, which like the coloured feathers of modern birds, might have facilitated crypsis, visual communication and/or thermoregulation in a cold polar habitat.

Keywords: Mesozoic birds, Aves, Paravesmelanosomes, Early Cretaceous

 Martin Kundrát, Thomas H. Rich, Johan Lindgren, Peter Sjövall, Patricia Vickers-Rich, Luis M. Chiappe and Benjamin P. Kear. 2019. A Polar Dinosaur Feather Assemblage from Australia. Gondwana Research. In Press. DOI: 10.1016/j.gr.2019.10.004 

Researchgate.net/publication/254219016_A_polar_dinosaur-track_assemblage_from_the_Eumeralla_Formation_Albian_Victoria_Australia

First evidence of feathered polar dinosaurs found in Australia - Uppsala University  mynewsdesk.com/uk/uu/pressreleases/first-evidence-of-feathered-polar-dinosaurs-found-in-australia-2942524 

[Paleontology • 2017] Serikornis sungei • A New Jurassic Theropod from China Documents A Transitional Step in the Macrostructure of Feathers

Serikornis sungei
Lefèvre, Cau, Cincotta, Hu, Chinsamy, Escuillié & Godefroit, 2017

DOI: 10.1007/s00114-017-1496-y  

 Illustration: E. Willoughby EmilyWilloughby.com

theropoda.blogspot.com

  

Abstract

Genuine fossils with exquisitely preserved plumage from the Late Jurassic and Early Cretaceous of northeastern China have recently revealed that bird-like theropod dinosaurs had long pennaceous feathers along their hindlimbs and may have used their four wings to glide or fly. Thus, it has been postulated that early bird flight might initially have involved four wings (Xu et al. Nature 421:335–340, 2003; Hu et al. Nature 461:640–643, 2009; Han et al. Nat Commun 5:4382, 2014). Here, we describe Serikornis sungei gen. et sp. nov., a new feathered theropod from the Tiaojishan Fm (Late Jurassic) of Liaoning Province, China. Its skeletal morphology suggests a ground-dwelling ecology with no flying adaptations. Our phylogenetic analysis places Serikornis, together with other Late Jurassic paravians from China, as a basal paravians, outside the Eumaniraptora clade. The tail of Serikornis is covered proximally by filaments and distally by slender rectrices. Thin symmetrical remiges lacking barbules are attached along its forelimbs and elongate hindlimb feathers extend up to its toes, suggesting that hindlimb remiges evolved in ground-dwelling maniraptorans before being co-opted to an arboreal lifestyle or flight.

Keywords: Paraves, Birds, Feathers, Barbules, Jurassic, Flight evolution

 the basal bird Serikornis sungei sp. nov. [PMOL-AB00200] from the Middle-Late Jurassic of north-eastern China. 

Fig. 1 Photograph and drawing of the basal bird Serikornis sungei sp. nov. from the Middle-Late Jurassic of north-eastern China.
 a PMOL-AB00200 photograph. b Line drawing.

 Abbreviations: cev cervical vertebrae, co coracoids, cv caudal vertebrae, fu furcula, il ilium, is ischium, lf left femur, lfi left fibula, lh left humerus, lma left manus, lpes left pes, lr left radius, ls left scapula, lt left tibia, lu left ulna, pu pubis, ra radiale, rf right femur, rh right humerus, rma right manus, rpes right pes, rr right radius, rt right tibia, ru right ulna, sk skull

Systematic palaeontology

Theropoda Marsh, 1881

Maniraptora Gauthier, 1986

Paraves Sereno, 1997; Avialae Gauthier, 1986

Serikornis sungei gen. et sp. nov.

Etymology: Serikos, ancient Greek for silk, because the body is almost covered with plumulaceous-like feathers; Ornis, ancient Greek for bird; named in honour of Sun Ge, for his contribution to our knowledge of Jurassic and Cretaceous ecosystems in Asia.

Holotype: PMOL-AB00200 is a single complete articulated skeleton with associated integumentary structures preserved on a slab. The counterpart is missing, but most of the skeleton is preserved on the main slab.

Locality and horizon: PMOL-AB00200 was collected in the Tiaojishan Formation (Oxfordian, Upper Jurassic; Chu et al. 2016) from Daxishan village, Linglongta (Jianchang County, Liaoning Province, China).

Diagnosis: Serikornis is characterized by the following combination of characters (autapomorphies are marked with an asterisk): four anterior maxillary teeth twice as long as the others regarding the crown height*; coracoid tuber well-developed and laterally projected from the lateral margin of the coracoid and forming a subglenoid shelf along the caudoventral margin of the bone; the distal end of the lateral process of the coracoid is thicker than the proximal part and forms a ventral rounded bump; ventrodistal process of ischium narrow, hook-like, strongly deflected caudodorsally and set at the distal end of the ischium*; smooth ventral side of coracoid devoid of small pits.

....

Illustration: Emily Willoughby EmilyWilloughby.com

 facebook.com/photo.php?fbid=10100308789191064 

Ulysse Lefèvre, Andrea Cau, Aude Cincotta, Dongyu Hu, Anusuya Chinsamy, François Escuillié and Pascal Godefroit. 2017. A New Jurassic Theropod from China Documents A Transitional Step in the Macrostructure of Feathers. The Science of Nature. 104:74. DOI: 10.1007/s00114-017-1496-y 

facebook.com/photo.php?fbid=10100308789191064

facebook.com/photo.php?fbid=10213490546476049

EmilyWilloughby.com/gallery/paleoart/the-silky-serikornis

theropoda.blogspot.com/2017/08/serikornis-per-gli-amici-silky.html

    

[Paleontology • 2017] Jianianhualong tengi • Mosaic Evolution in An Asymmetrically Feathered Troodontid Dinosaur with Transitional Features

Jianianhualong tengi  

Xu, Currie, Pittman, Xing, Meng, Lü, Hu & Yu, 2017 

 Life reconstruction by Julius T. Csotonyi | DOI: 10.1038/ncomms14972

Abstract
Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Here we report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical features that are transitional between long-armed basal troodontids and derived short-armed ones, shedding new light on troodontid character evolution. It indicates that troodontid feathering is similar to Archaeopteryx in having large arm and leg feathers as well as frond-like tail feathering, confirming that these feathering characteristics were widely present among basal paravians. Most significantly, the taxon has the earliest known asymmetrical troodontid feathers, suggesting that feather asymmetry was ancestral to Paraves. This taxon also displays a mosaic distribution of characters like Sinusonasus, another troodontid with transitional anatomical features.

Figure 1: Jianianhualong tengi holotype DLXH 1218.
 (a) Photograph and (b) line drawing of the specimen. Scale bar, 50 cm.

 cav, caudal vertebrae; cv, cervical vertebrae; dv, dorsal vertebrae; fu, furcula; lfe, left femur; lh, left humerus; li, left ilium; lis, left ischium; lm, left manus; lp left pes; lpu, left pubis; lr, left radius; lu, left ulna; md, mandible; rc, right coracoid; rfe, right femur; rfi, right fibula; rh, right humerus; ri, right ilium; rm, right manus; rr, right radius; rs, right scapula; rt, right tibiotarsus; ru, right ulna; sk, skull; ss, synsacrum. 

Figure 7: Life reconstruction of Jianianhualong tengi based on the holotype DLXH 1218.

by Julius T. Csotonyi 

Systematic palaeontology 

Theropoda Marsh, 188121
Coelurosauria Huene, 192022

Maniraptora Gauthier, 198623
Troodontidae Gilmore, 192424

Jianianhualong tengi gen. et sp. nov.

 Etymology. ‘Jianianhua’, the Chinese company that supported this study; ‘long’, the Chinese Pinyin for dragon. The specific name honors Ms Fangfang Teng, who secured the specimen for study.

 Holotype. DLXH 1218, a nearly complete skeleton with associated feathers (Fig. 1) housed at the Dalian Xinghai Museum.


Locality and horizon. Baicai Gou, Yixian County, western Liaoning, China; Lower Cretaceous Yixian Formation.

 Diagnosis. A troodontid distinguishable from other taxa in possessing the following apomorphic features (*indicates autapomorphic feature): maxillary rostral ramus triangular in outline and relatively high dorsoventrally*; maxillary ascending process extending posterodorsally at a high angle (an angle of ∼45° to maxillary ventral margin)*; lacrimal with a long descending process sub-equal in length to anterior process; a prominent ridge along anterior edge of the lateral surface of the lacrimal descending process; a distinct fossa on the dorsal surface of the surangular close to its posterior end; axial neural spine with a convex dorsal margin, transversely thickened anterior margin, and posterodorsal portion expanding strongly posteriorly; long manual phalanx II-1 (slightly shorter than metacarpal III) with prominent proximoventral heel, large groove along the medial surface of more than proximal half of manual phalanx II-1*; highly elongated manual III-2 (slightly longer than metacarpal III)*; robust ungual phalanges (medial ungual proximal depth/ungual length ratio >0.5); ilium with slightly concave dorsal margin in lateral view*; small medial lamina along ischial obturator process dorsal margin; metatarsal IV without prominent ventral flange*.

Figure 2: Cranium of Jianianhualong tengi holotype DLXH 1218.
 (a) Photograph and (b) line drawing of the skull and mandible. Scale bar, 2 cm.

ax, axis; fg, groove with foramina; fo, fossa; imf, internal mandibular fenestra; la, left angular; ld, left dentary; lect, left ectopterygoid; lex, left exoccipital; lf; left frontal; lhy, left hyoid bone; lj, left jugal; lla, left lacrimal; lm, left maxilla; lmf, left maxillary fenestra; ln, left nasal; lp, left parietal; lpt?, left pterygoid?; lpa, left prearticular; lpo, left postorbital; lpsaf, left posterior surangular foramen; lsa, left surangular; lsp?, left splenial?; lso, left supraoccipital; lsq, left squamosal; mc, Meckelian canal; ra, right angular; rart, right articular; rd, right dentary; rf, right frontal; rhy, right hyoid bone; rm?, right maxilla?; rn; right nasal; rp, right parietal; rpa, right prearticular; rq?, right quadrate?; rsa; right surangular; rso, right supraoccipital; rsp; right splenial; rsq, right squamosal. 

Xing Xu, Philip Currie, Michael Pittman, Lida Xing, Qingjin Meng, Junchang Lü, Dongyu Hu and Congyu Yu. 2017. Mosaic Evolution in An Asymmetrically Feathered Troodontid Dinosaur with Transitional Features.
  Nature Communications. 8, Article number: 14972.  DOI: 10.1038/ncomms14972

New Birdlike Dinosaur Had Modern Feathers on.natgeo.com/2p20KoN  @NatGeo

  

[Paleontology • 2017] New Specimens of Anchiornis huxleyi (Theropoda, Paraves) from the late Jurassic of northeastern China

Abstract

Four new specimens of Anchiornis huxleyi (PKUP V1068, BMNHC PH804, BMNHC PH822, and BMNHC PH823) were recently recovered from the late Jurassic fossil beds of the Tiaojishan Formation in northeastern China. These new specimens are almost completely preserved with cranial and postcranial skeletons. Morphological features of Anchiornis huxleyi have implications for paravian character evolution and provide insights into the relationships of major paravian lineages. Anchiornis huxleyi shares derived features with avialans, such as a straight nasal process of the premaxilla and the absence of an external mandibular fenestra in lateral view. However, Anchiornis huxleyi lacks several derived deinonychosaurian features, including a laterally exposed splenial and a specialized raptorial pedal digit II. Morphological comparisons strongly suggest Anchiornis is more closely related to avialans than to deinonychosaurians or troodontids. Anchiornis huxleyi exhibits many conservative paravian features, and closely resembles Archaeopteryx and other Jurassic paravians from Jianchang County, such as Xiaotingia and Eosinopteryx. The other Jianchang paravian, Aurornis xui, is likely a junior synonym of Anchiornis huxleyi.

Rui Pei, Quanguo Li, Qingjin Meng, Mark Norell and Keqin Gao. 2017. New Specimens of Anchiornis huxleyi (Theropoda, Paraves) from the late Jurassic of northeastern China. Bulletin of the American Museum of Natural History. 411.  URI: hdl.handle.net/2246/6707

  

[PaleoEcology / Paleontology • 2016] Dental Disparity and Ecological Stability in Bird-like Dinosaurs Prior to the End-Cretaceous Mass Extinction

A small feathered dinosaur swoops down on an unsuspecting lizard while a bird hunts for seeds in this reconstructed slice of life in Alberta 66 million years ago. A new theory suggests that a seed diet helped birds survive the mass extinction event that wiped out all other dinosaurs.

illustration: Danielle DUFAULT

 DOI:  10.1016/j.cub.2016.03.039 

Highlights

• Tooth shape disparity in small maniraptoran dinosaurs is examined in the Cretaceous

• Results show stability and sudden extinction in this guild at the end of the Cretaceous

• Groups are mostly static in shape space except for larger size in the early Maastrichtian

• Evolution of an edentulous beak and granivory may have been key to the survival of birds

Summary

The causes, rate, and selectivity of the end-Cretaceous mass extinction continue to be highly debated. Extinction patterns in small, feathered maniraptoran dinosaurs (including birds) are important for understanding extant biodiversity and present an enigma considering the survival of crown group birds (Neornithes) and the extinction of their close kin across the end-Cretaceous boundary. Because of the patchy Cretaceous fossil record of small maniraptorans, this important transition has not been closely examined in this group. Here, we test the hypothesis that morphological disparity in bird-like dinosaurs was decreasing leading up to the end-Cretaceous mass extinction, as has been hypothesized in some dinosaurs. To test this, we examined tooth morphology, an ecological indicator in fossil reptiles, from over 3,100 maniraptoran teeth from four groups (Troodontidae, Dromaeosauridae, Richardoestesia, and cf. Aves) across the last 18 million years of the Cretaceous. We demonstrate that tooth disparity, a proxy for variation in feeding ecology, shows no significant decline leading up to the extinction event within any of the groups. Tooth morphospace occupation also remains static over this time interval except for increased size during the early Maastrichtian. Our data provide strong support that extinction within this group occurred suddenly after a prolonged period of ecological stability. To explain this sudden extinction of toothed maniraptorans and the survival of Neornithes, we propose that diet may have been an extinction filter and suggest that granivory associated with an edentulous beak was a key ecological trait in the survival of some lineages.

Figure 2: Tooth Disparity Through Time – A plot of tooth disparity (shape variation) thought the last 20 million years of the Cretaceous from the four groups of bird-like dinosaurs analyzed in this study.

DOI:  10.1016/j.cub.2016.03.039  

A small feathered dinosaur swoops down on an unsuspecting lizard while a bird hunts for seeds in this reconstructed slice of life in Alberta 66 million years ago. A new theory suggests that a seed diet helped birds survive the mass extinction event that wiped out all other dinosaurs.

illustration: Danielle DUFAULT

Derek W. Larson, Caleb M. Brown and David C. Evans. 2016. Dental Disparity and Ecological Stability in Bird-like Dinosaurs Prior to the End-Cretaceous Mass Extinction. Current Biology.  DOI:  10.1016/j.cub.2016.03.039

Fossil teeth suggest that seeds saved bird ancestors from extinction http://esciencenews.com/node/1250215

Why did birds live while dinosaurs died? It’s a seedy story, researchers say /via @globeandmail http://www.theglobeandmail.com/technology/science/why-did-birds-live-while-dinosaurs-died-its-a-seedy-story-researcherssay/article29705574

Fossil teeth suggest that seeds saved bird ancestors from extinction https://www.sciencedaily.com/releases/2016/04/160421133639.htm