Review of 2019

Last year I didn't quite keep up the "at least one post every month" streak that I managed in 2018, but I did maintain what I think was a somewhat reasonable posting frequency. Furthermore, I made several major overhauls or additions to the blog, namely a list of extinct Cenozoic bird genera and a rewritten "About" page. I even found time to draw a handful of answers for the Raptormaniacs askblog, imagine that. Travel-wise, I attended ProgPal, SVP, and TetZooCon, with SVP being particularly notable in that it allowed me to visit Australia (and the Southern Hemisphere overall) for the first time.

Probably the biggest personal event of last year relevant to the content and themes of this blog was that I got the first part of my PhD research published as a peer-reviewed scientific paper. In this study, my coauthors and I combined genetic and fossil data to investigate the controversial phylogentic relationships of strisorean birds (nightjars, swifts, hummingbirds, etc.). The paper can be read for free here and I also blogged about it here.

My paper on strisorean phylogeny made the journal cover!

Onward to the annual review of new maniraptor research! In January, photoluminescence in the bills of Atlantic puffins was reported. The structure and chemistry of a fossil feather from the Crato Formation was characterized. A feathered enantiornithean foot preserved in amber was described. Conspicuous plumage in fairy wrens was shown not to increase predation risk. New Caledonian crows were found to be able to infer the weight of objects from watching their movements when blown by the wind. New studies came out on the molecular evolution of maniraptor feathers, the cranial anatomy of Beipiaosaurus, and the diversification of trogons. Newly-named maniraptors included the enantiornithean Shangyang graciles, the stem-anseriform Conflicto antarcticus, and the zygodactylid Zygodactylus ochlurus.

Skull of the holotype of Conflicto antarcticus, from Tambussi et al. (2019).

In February, the isolated holotype feather of Archaeopteryx was reevaluated and its assignment to Archaeopteryx was questioned. A thermoregulatory function was documented for cassowary casques. Bill flourescence was reported in rhinoceros auklets. A supposed ibis from the Eocene of Antarctica was reinterpreted as a chimaeroid fish. The pectoral musculature of the European starling was reconstructed in 3D. New studies came out on the evolution of avian cranial morphology, the avian syrinx, and furnariidan plumage brightness, social parasitism in greater anis, the phylogenetic position of adzebills, the Eyles's harrier, and the Haast's eagle, the genomics of raptorial birds, hunting success and flight mechanics in peregrine falcons, metatool problem solving and material selectivity during tool crafting in New Caledonian crows, the rejection of brood parasite eggs by tawny-flanked prinias and chalk-browed mockingbirds, spatial cognition in mountain chickadees, social network position in zebra finches, and the loss of maternal care in icterids. Newly-named maniraptors included the oviraptorosaur Gobiraptor minutus, the Paleocene anseriform Naranbulagornis khun, the recently extinct penguin Eudyptes warhami, the stem-upupidean Laurillardia smoleni, and the stem-passerines Eofringillirostrum boudreauxi and Eofringillirostrum parvulum.

Holotype of Eofringillirostrum boudreauxi, from Ksepka et al. (2019).

In March, preserved feathers were documented in a juvenile enantiornithean specimen from the Calizas de La Huérguina Formation, contrary to previous reports that none had been preserved. New studies came out on bone histology of Yanornis, the distribution of medullary bone in the avian skeleton, the phylogeny of Dendrortyx, Psittacula (sensu lato) and orioles, the taxonomic status of the great white heron, ultraviolet sensitivity in owls, and factors affecting the vocalizations American crows make around food. Newly-named maniraptors included the therizinosaur Lingyuanosaurus sihedangensis, the enantiornithean Avimaia schweitzerae, and the cream-eyed bulbul (Pycnonotus pseudosimplex).

Holotype of Avimaia schweitzerae, from Bailleul et al. (2019). Note the unlaid egg preserved in its body cavity.

In April, amino acids were recovered from Cretaceous and Eocene feathers preserved in amber. Possible flapping adaptations were identified in Archaeopteryx. The taxonomic utility of ancient avian collagen was assessed. Female song in songbirds was reviewed. Memory performance was shown to influence male reproductive success in North Island robins. Plunge-diving was reported as an anti-predator behavior in the white-banded swallow. New studies came out on bone histology of Xixianykus, the scaling of avian osteocyte lacunae, the evolution of feather barbules, avian digestive enzymes, plumage patterns in woodpeckers, color dichromatism in tyrannidans, sex chromosomes in songbirds, and nectarivory in honeyeaters, the phylogeny of paleognaths, passerines, honeyeaters, white-eyes, and West Indian mimids, the convergent loss of flight in paleognaths, the growth of chicken beaks, the dispersal and speciation of tityrines, and convergent plumage evolution in Marquesan reed warblers. Newly-named maniraptors included the oviraptorosaur Xingtianosaurus ganqi, the indeterminate paravian Imperobator antarcticus, the Miocene heron Taphophoyx hodgei, and the Miocene bristlebird Dasyornis walterbolesi.

(Partial) phylogeny of passerines, from Oliveros et al. (2019).

In May, giant oviraptorosaur eggs were described from the Wayan Formation. Mechanisms of auditory species recognition in birds was reviewed. Dryolimnas rails were found to have evolved flightlessness more than once on Aldabra. Food caches were shown to augment song quality in male bull-headed shrikes. New studies came out on the structure of maniraptor eggshells, flapping inducement in Caudipteryx, the correlation of avian neck and leg length, ancient DNA in rhea, the architecture of cancellous bone in moa hindlimbs, the evolution of flightlessness in steamer ducks, drag reduction in kingfishers, and skull shape in parrots, vocal and visual learning in long-billed hermits, locomotion in juvenile hoatzins, the phylogenetic position of adzebills (clashing with the study from earlier in the year), talon shape in raptorial birds, the phylogeny of cuckooshrikes, the taxonomy of the blue-throated flycatcher species complex, and color perception in zebra finches. Newly-named maniraptors included the scansoriopterygid Ambopteryx longibrachium and the basal avialan Alcmonavis poeschli. The new name Camptodontornis was coined as a replacement for the enantiornithean genus "Camptodontus" (preoccupied by a beetle), though it should be noted that previous studies had already considered this genus likely synonymous with Longipteryx.

Falkland steamer ducks, photographed by In Vitrio, under CC BY-SA 4.0.

In June, the plumage coloration of Eocoracias was inferred. The origin of feathers and interspecies hybridization in birds was reviewed. New specimens of Gargantuavis, Pachystruthio (formerly considered synonymous with Struthio), Cayaoa, and Pellornis were described. The cranial anatomy of the rock pigeon was digitally dissected. Nocturnal torpor in superb fairy wrens and novel vocalizations in female cerulean warblers were documented. New studies came out on the development of avian fingers, the influence of climate change on avian distribution through time, the phylogenetic position of Cayaoa and Becassius, the genetic basis of feathered feet in pigeons, the energetic benefits of flocking in pigeons, the function of major call types in common cuckoos, incipient speciation between Kentish and white-faced plovers, acceleration during wing-propelled swimming in auks, forelimb musculature of diurnal raptors, and the phylogeny of weaverbirds. Newly-named maniraptors included the stem-galliform Xorazmortyx turkestanensis, the Miocene shorebird Cherevychnavis umanskae, the whistling long-tailed cuckoo (Cercococcyx lemaireae), and the western yellow-spotted barbet (Buccanodon dowsetti).

Restoration of Eocoracias with inferred plumage coloration, from Babarović et al. (2019).

In July, a sulphur-crested cockatoo was reported to exhibit spontaneous and diverse movement to music. Feathers were suggested to exemplify the generation of novel adaptive structures through sexual selection. The histology of caenagnathid jaws was used to argue that they did not lose teeth through ontogeny, contrary to other recent studies. A new specimen of Phorusrhacos was described, as was a new specimen of Microraptor with a new species of lizard preserved in its body cavity. A supertree of neornitheans was presented. An avian femur from the López de Bertodano Formation, formerly suggested to be a cariamiform, was reevaluated as a large specimen of Vegavis. New studies came out on rates of morphological evolution in Mesozoic avialans, the evolution of brain shape in flying archosaurs (including birds), the homology of avian fingers, the ontogeny of avian femora and ostrich pelvic musculature, the role of wing coloration in avian flight efficiency, the diversification of Amazonian birds, the flight style of Calciavis, differentiation between torrent duck populations, variation in the inner ear labyrinth of wild turkeys, the phylogeny of neoavians, anhingas, Catharus, and open-habitat chats, aerial maneuvering by rosy-faced lovebirds, and parallel adaptation to salt marshes in passerellids. Newly-named maniraptors included the long-awaited troodont Hesperornithoides miessleri, the enantiornithean Elektorornis chenguangi, the recently extinct rail Dryolimnas chekei, and the Pliocene albatross Aldiomedes angustirostris.

Skeletal reconstruction of Hesperornithoides miessleri, from Hartman et al. (2019).

In August, New Caledonian crows were reported to behave more optimistically after tool use. The Canary Islands oystercatcher was suggested to be a subspecies or morph of the Eurasian oystercatcher. Herring gulls were found to respond to human gaze direction. Glaucous-winged gulls were recorded kleptoparasitizing sea otters and sea lions. A large eagle from the Pleistocene-Holocene of the Dominican Republic was described, as was a new specimen of Anthropornis. Chickadees were shown to prefer conspecific odors. New studies came out on nest arrangement in oviraptorids, the function of dromaeosaurid sickle claws, the plumage of juvenile enantiornitheans, the development of avian foot scales, the composition of avian urinary excreta, the evolution of juvenile pheomelanin-based coloration in birds, seasonal plumage coloration in passerines, and female promiscuity in passerideans, trade-offs between locomotion and reproduction in kiwi, the morphology of the hypotarsal in ralloids and toepads in Australian birds, the phylogenetic position of Caracara creightoni, the phylogeny of shrikes, energy conservation in garden warblers, and female song in eastern bluebirds. Newly-named maniraptors included the alvarezsaur Shishugounykus inexpectus, the Paleocene penguin Crossvallia waiparensis, and the large Miocene parrot Heracles inexpectatus. Oh, and my paper on strisorean phylogeny was published, in case you missed that earlier.

Juvenile enantiornithean with close-ups of its plumage, from O'Connor et al. (2019).

In September, the cranial anatomy of a new specimen of Saurornitholestes was described. The genomes of all extant penguins were presented. White plumage was shown to be advantageous for barn owls hunting on moonlit nights. New studies came out on the taphonomy of keratin and melanosomes in feathers, the evolution of the palate in paravians, the relationship between avian foot claws and their keratin sheaths, bone laminarity in emus, adaptations for high-altitude flight in bar-headed geese, the phylogeny of strisoreans and coraciiforms, the taxonomy of the collared owlet species complex, and the correlation between song repertoire and plasticity in songbirds. Newly-named maniraptors included the early pelagornithid Protodontopteryx ruthae and the Pliocene-Pleistocene ibis Geronticus thackerayi. The name Heyuanninae was coined as a replacement for "Ingeniinae".

Skull of the holotype of Protodontopteryx ruthae, from Mayr et al. (2019).

In October, the male white bellbird was reported producing the loudest recorded call of any bird. An enantiornithean foot and tail feather preserved in amber were described. Range of motion in the avian wing was found to correlate with flight style. Darker pigmentation in avian eggshells was suggested to confer a thermoregulatory benefit. Differently sized cuckoos were shown to pose different threats to their hosts. A novel organelle in the retina of Empidonax flycatchers was documented. New studies came out on skull evolution in oviraptorosaurs, the hindlimb morphology of Palaeotis, skeletal development in ducks, the lunar cycle as a driver of migration for European nightjars, the taxonomy of the South American snipe, the thermoregulatory function of tufted puffin bills, food wasting by parrots, the phylogeny of passerines, delayed gratification in New Caledonian crows, breeding behavior in phainopeplas, and memory inception in zebra finches. Newly-named maniraptors included the alvarezsaur Nemegtonykus citus, the enantiornithean Gretcheniao sinensis, the recently extinct quail Coturnix alabrevis, Coturnix centensis, and Coturnix lignorum, the indeterminate Oligocene bird Carpathiavis meniliticus, the Alor myzomela (Myzomela prawiradilagae), and the spectacled flowerpecker (Dicaeum dayakorum).

Male white bellbird calling, from Podos and Cohn-Haft (2019).

In November, evidence of hatching asynchrony in oviraptorid clutches was presented. An assemblage of fossil feathers from the Early Cretaceous of Australia was reported. Vulturine guineafowls were recorded forming multilevel societies. Scavenging behavior in owls was reviewed. Parrots were found to lack aversion to inequity. New studies came out on the structure of flight feathers, the evolution of the avian digestive system, beak preservation in Confuciusornis, the origin of the euornithean predentary, the biogeography of hesperornithiforms, correlation between avian egg and nest characteristics, otic morphology in neognaths, variation in the crest of helmeted guineafowl, nest associations between rough-legged hawks and peregrine falcons, cooperative breeding in chestnut-crested yuhinas, diversification rates in emberizoids, and auditory learning in brown-headed cowbirds. Newly-named maniraptors included the basal avialan Fukuipteryx prima, the Cretaceous euornitheans Mengciusornis dentatus and Antarcticavis capelambensis, the Miocene emu Dromaius arleyekweke, the recently extinct pigeon Ducula shutleri, the recently extinct rail Hypotaenidia vavauensis, and the eogruid Sinoergilornis guangheensis.

Vulturine guineafowl, photographed by Ninara, under CC BY 2.0.

In December, Tereingaornis was reevaluated and considered a dubious taxon. Evidence for mixed-age flocking in avimimids was reported. Rachis-dominated feathers preserved in amber were described. The genomes of the Carolina parakeet and the superb fairy wren were presented. New studies came out on the evolution of feather barb angles and honeyeater beaks, the flight style of Protopteryx, the recovery of ruffled feather vanes in birds, syrinx and hyoid morphology in southern cassowaries, the former population densities of moa, respiration kinematics in wild turkeys, the loss of flight in the Aldabra white-throated rail, the function of juvenile ornamentation in American coots, vision speed in raptorial birds, the phylogeny of owls, the taxonomy of the blue-backed parrot, and begging suppression in young red-winged blackbirds. Newly-named maniraptors included the enantiornithean Mirusavis parvus, the Cretaceous ornithuran Kookne yeutensis, and the Paleocene penguin Kupoupou stilwelli.

American coot with chicks, photographed by Casey Klebba, under CC BY-SA 4.0.