Wednesday, January 3, 2018

Review of 2017

Activity on this blog took a dip last year, most likely on account of me finishing up work for my Master's degree and starting my PhD. Perhaps also reflecting these events, I attended more conferences last year than in the past, among them ProgPal, SVP, TetZooCon, and PalAss. As for visits to zoos, museums, and other notable attractions, the highlight was probably my trip to the temporary Dinosaurs of China exhibit in Nottingham.

Regrettably, other than a handful of Tumblr posts and a parody during April Fools', I didn't draw anything new for the Raptormaniacs comic at all. Though the prospects of doing long-form storylines in the foreseeable future are uncertain, I hope to produce material for at least the Tumblr askblog somewhat more regularly over the coming year.

It would be wrong to say that this blog completely stagnated, however, as it was last year that I decided to start writing more detailed blog posts about new scientific studies on maniraptors. The opportunity to work on these posts was (and will be) highly contingent on my possession of increasingly mythical free time, but on the whole I was personally quite satisfied with the few articles that I was able to produce. As such, they will likely continue to be a recurring feature on this blog in the future.

I may not have made many comics last year, but I did take some time to draw some fun things such as this field guide to Mesozoic Twitter birds.

Speaking of new studies, it's time for the annual overview of maniraptor-related discoveries that were published over the past year. In January, new material of Garganornis was described. A record number of yellow-billed oxpeckers (51-60 individuals) was reported feeding on a single host. Elephant bird DNA was extracted from eggshell material. New studies came out on the coevolution of pygostyle morphology and tail feathers in Mesozoic avialans, the migration of Kirtland's warblers, hind limb morphometrics of phorusrhacids, the cranial osteology of Buitreraptor, the phylogeny of aquiline eagles, correlation between avian footprint and wing morphology, and phalangeal joint kinematics in ostriches. Newly-named maniraptors included the Eocene penguin Aprosdokitos mikrotero and the enantiornithine Cruralispennia multidonta.

Holotype of Cruralispennia multidonta, from Wang et al. (2017).

In February, a new female specimen of Eoconfuciusornis provided insights into its soft tissue and coloration. New material of Gargantuavis was described, as was a Paleocene penguin from the Waipara Greensand. External morphological measurements were documented for a variety of passerines. New studies came out on sentinel behavior in Arabian babblers, group behavior in chimney swifts during approaches to their roost, the function of egg shape in murres and cranial fenestration in neornithines, seed dispersal by mallards, the evolution of gestural displays in icterids and nest shape in passerines, and the macroevolutionary dynamics of bill evolution in neornithines. Newly-named maniraptors included the Miocene anhinga Macranhinga ameghinoi and the Eocene charadriiform-like bird Vanolimicola longihallucis.

Well-preserved Eoconfuciusornis specimen with feather melanosomes highlighted in insets, from Zheng et al. (2017).

In March, the soft tissues of Anchiornis were described using laser fluorescence. The bald head of northern bald ibises was shown to have a thermoregulatory function. Sociality was found to be inversely correlated with brain size in woodpeckers, unlike the pattern seen in some mammal groups. Kea were discovered to produce a specific vocalization that likely functions similarly to laughter. Preserved tendons/ligaments and cartilage in Confuciusornis and their functional implications were reported. New studies came out on craniofacial diversification in domestic pigeons, functional niche partitioning in therizinosaurs, adjustment of migration in a newly-established population of barn swallows, bone histological correlates of flight style in birds, scaling of owl hind limbs, social dynamics in non-breeding common ravens, pectoral girdle morphology in Mesozoic avialans, the phylogenetic position of the São Tomé grosbeak, and sources of conflict in resolving neornithine phylogeny. Newly-named maniraptors included the Miocene rhea Opisthodactylus kirchneri and the Tatamá tapaculo (Scytalopus alvarezlopezi).

Foot pads of Anchiornis revealed under laser fluorescence, from Wang et al. (2017).

In April, the neural basis of species recognition in brown-headed cowbirds was identified. New specimens of Anchiornis were described. A volume on the avian respiratory system was published. New studies came out on the migratory connectivity of semipalmated sandpipers, turn-taking ceremonies in common murres, and cumulative culture in pigeons. Newly-named maniraptors included the dromaeosaurid Zhongjianosaurus yangi, the enantiornithine Piscivorenantiornis inusitatus, and the Miocene rails Crexica crexica and Miohypotaenidia tanaisensis.

Juvenile brown-headed cowbird, photographed by Bill Bouton, under CC BY-SA 2.0.

In May, Egyptian vultures were reported to use soil as cosmetics. Common ravens were shown to remember deceptive behavior from other individuals for over a month. New studies came out on the safekeeping of tools by Goffin's cockatoos, the energetics of foraging flight in Pacific parrotlets, oxygen isotope fractionation between bird bone and drinking water, the diversification of capuchino seedeaters, the evolution of beak shape in waterfowl, the function of slotted wing tips during flight in Eurasian jackdaws, and the balancing mechanism of flamingos while standing on one leg. Newly-named maniraptors included the oviraptorosaur Beibeilong sinensis (based on an embryo long known as "Baby Louie"), the troodonts Jianianhualong tengi and Liaoningvenator curriei, and the dry forest sabrewing (Campylopterus calcirupicola). 2017 could well be considered the Year of the Troodontid for dinosaur paleontology, given that several other new troodont taxa would be named in the coming months.

Pacific parrotlet, photographed by "peterdehaas2317" and modified by "Snowmanradio", under CC BY 2.0.

In June, a nearly complete juvenile enantiornithine was reported preserved in amber. The genetic signature of flightlessness in flightless cormorants was identified. The supposed Miocene auk Petralca was reevaluated as a loon. A new specimen of Buitreraptor was described. Neomorphus cuckoos were suggested to deter predators by mimicking sounds made by peccaries. Seasonally conspicuous plumage was found to prompt risk avoidance in male superb fairy-wrens. New studies came out on the determination of flightlessness in extinct anatids, the function of avian egg shape and double kneecaps in ostriches, the historical range of the Carolina parakeet, the migration of gray-cheeked thrushes, the incubation temperatures of oviraptorosaur eggs, the allometry of pelvic dimensions in birds, and rhythmic drumming in palm cockatoos. Newly-named maniraptors included the Oligocene albatross Diomedavus knapptonensis, the troodont Daliansaurus liaoningensis, the Pleistocene megapodes Garrdimalga mcnamarai, Latagallina naracoortensis, Latagallina olsoni, and Progura campestris, the recently extinct Greater Azores bullfinch (Pyrrhula crassa), and the blue-winged amazon (Amazona gomezgarzai).

Juvenile enantiornithine preserved in amber, from Xing et al. (2017).

In July, common ravens were shown to be capable of planning for future tool use and bartering. Blue petrels were found to be able to recognizing their own eggs by scent. The Liberian greenbul was argued to be a plumage variant of the icterine greenbul. Neornithines were suggested to have undergone a reduction in body size across the K-Pg extinction. Osteomyelitis was documented in an Eocene penguin. Kelp gulls and dolphin gulls were reported to inflict perineal wounds on South American fur seal pups. New Zealand swans were confirmed to have represented a distinct, now-extinct lineage from extant black swans. Japanese tits were discovered to decode novel code sequences using the ordering of specific vocalizations. New studies came out on the osteology of Neuquenraptor, the developmental pathways leading to flightlessness in paleognaths, the biogeographic history of accentors, the bone microstructure of Vegavis, song discrimination in Neotropical passerines, wing development in emus, joint mobility in the avian neck, correlated evolution between sternal keel length and ilium length in birds, camouflage in ground-nesting birds, and the flight style of Sapeornis. Newly-named maniraptors included the Paleocene stem-mousebird Tsidiiyazhi abini, the troodont Albertavenator curriei, and the oviraptorosaur Corythoraptor jacobsi.

Diagram showing the likely soaring capabilities of Sapeornis, from Serrano and Chiappe (2017).

In August, the eggs of Heyuannia were shown to have been blue-green in color. The atlas rib of Archaeopteryx was reported for the first time. "Tasidyptes" was demonstrated to be an invalid taxon, being based on remains of several extant penguin species. Complex plumage patterns were found to be produced mainly with contribution from melanin pigments. The late Pleistocene passerines of Liang Bua in Indonesia were described. New studies came out on seed dispersal by macaws, the bone histology of Daliansaurus and dodos, object categorization by tits, the cranial morphology of Avimimus, the migration of penguins, the dominance hierarchy of North American birds, the kinematics of ostrich knees, skeletal traits shaped by embryonic activity in birds, recognition of individual eggs by house sparrows, the evolution of avian intelligence and senses, and the range of motion in avian hind limbs. Newly-named maniraptors included the hesperornithine Chupkaornis keraorum, the troodont Latenivenatrix mcmasterae, the anchiornithid Serikornis sungei, and the recently extinct kohatu shag (Leucocarbo septentrionalis). Stenonychosaurus was resurrected as a valid taxon, the name Troodon becoming restricted to the original holotype tooth.

The eggs of Heyuannia and their inferred coloration, from Wiemann et al. (2017).

In September, Sapeornis and caenagnathids were shown to have lost tooth sockets through ontogeny. The calls of female common cuckoos were found to misdirect the defenses of their hosts. Okarito kiwis were reported to be capable of surviving in the wild without eyesight. Barn owls were discovered not to experience hearing loss with age. Complex songs from conspecifics were demonstrated to elicit greater aggression in tui. New studies came out on the crafting of hook tools by Goffin's cockatoos, the diversification of anseriforms, the caudal anatomy of Buitreraptor, species recognition in Neotropical passerines, the wing morphing of hovering amazilia hummingbirds, cooperative feeding in African penguins, object exploration in kea and New Caledonian crows, and multitasking in pigeons. Newly-named maniraptors included the painted manakin (Machaeropterus eckelberryi).

Vestigial tooth sockets in (A) Caenagnathasia and (D) Sapeornis, from Wang et al. (2017).

In October, the phylogenetic positions of large flightless neognaths were evaluated. Vegavis, Polarornis, and Australornis were found to form a clade of stem-anseriforms. Selection for longer bills was observed in great tits in the United Kingdom. An alvarezsaurid from the Bissekty Formation was described. Territorial song was documented in female dark-eyed juncos. New studies came out on yellow feather pigmentation in budgerigars, bone fusion in Pterygornis, reconciliation in carrion crows, the preservation of preen gland oils in an Eocene bird, song recognition by golden-crowned sparrow nestlings, heterospecific eavesdropping in ant-following birds, wing allometry in hummingbirds, genome evolution in munias, ecological separation between Mesozoic avialans and pterosaurs, and cooperative breeding in birds. Newly-named maniraptors included the enantiornithine Junornis houi.

Phylogeny of neornithines with an emphasis on large flightless neognaths, from Worthy et al. (2017).

In November, Goffin's cockatoos were found to be capable of using simple keys. A confuciusornithid from the Huajiying Formation was described. A supposed oviraptorosaur from the Santana Formation was reevaluated as a megapraptoran. Whooping cranes were reported to associate with their future mates long before sexual maturity. The aerobic performance of tinamous was shown to be limited by their small heart size. Gastroliths were identified in several specimens of Jeholornis. Increased bill size was documented in snail kites, associated with the invasion of a novel prey item, the island apple snail. The regulatory modules involved in feather development were identified. New studies came out on the hindlimb musculature of foot-propelled swimming birds, the developmental basis of tactile specialization in ducks, song learning in zebra finches, sounds made using flight feathers in crested pigeons, correlation between aerobic power and flight style in birds, the origins of avian secondary temporal fenestrae, the functional anatomy of the Gigantoraptor jaw, the function of chick-carrying in eared grebes, convergent evolution in petroicids, feather structure in Anchiornis, the phylogeny of kingfishers, and genomic diversity in passenger pigeons. Newly-named maniraptors included the oviraptorosaur Avimimus nemegtensis and Guyramemua, a new genus for the chapada flycatcher.

Goffin's cockatoos matching shapes and suitable frames, from Habl and Auersperg (2017).

In December, a preserved retina was reported in an enantiornithine specimen. The fossil feather Praeornis was interpreted as a ribbon-like feather, such as those found on the tail of confuciusornithids and enantiornithines. The anatomical features associated with scent-based foraging in turkey vultures were identified. The ornamentation of male golden-crowned manakins was shown to have arisen through hybrid speciation. Phorusrhacid specimens from the late Pleistocene were described. A tick was found entangled in a Cretaceous pennaraptor feather. New studies came out on the evolution of crowned pigeons, the body mass of the dodo, magnitude coding of space and time by pigeons, tool shape variation in New Caledonian crows, the growth of dental tissues in therizinosaurs, the neuronal basis of imitative learning on swamp sparrows, the perception of male signals by female brown-headed cowbirds, the developmental origins of mosaic evolution in the avian skull, and the phylogenetic positions of Chendytes and the Labrador duck. Newly-named maniraptors included the anchiornithid Ostromia crassipes (based on a specimen long considered an individual of Archaeopteryx), the Cretaceous euornithine Maaqwi cascadensis, the Paleocene penguin Kumimanu biceae, the troodont Almas ukhaa, the semi-aquatic dromaeosaurid Halszkaraptor escuilliei, and the Cordillera Azul antbird (Myrmoderus eowilsoni).

Holotype and skeletal reconstruction of Halszkaraptor escuilliei with various notable aspects of its anatomy highlighted, from Cau et al. (2017).

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