Tuesday, January 1, 2019

Review of 2018

I made fewer than 20 posts on this blog last year, a foreseeable consequence of continuing work on my PhD. However, I'd like to draw attention to the fact that I wrote at least one post for every month of the year, a first in the history of Raptormaniacs! These posts included summaries of recent scientific discoveries about maniraptors (some of which have ended up being among the most popular posts on this blog) as well as the usual conference and trip reports. Last year, I attended ProgPal, IPC, SVP, and PalAss, presenting my ongoing research at each one. A personal highlight of 2018 was the fact that I got to speak at TetZooCon. I also enjoyed visiting Dinosaurs in the Wild and the French National Museum of Natural History.

I said last year that I would at least try to update the Raptormaniacs askblog more often in 2018, which... uh, didn't happen. This was, in part, the fault of Tumblr for flagging the askblog as explicit without notifying me, but I didn't exactly follow through once the issue had been cleared up either. Mark my words though: as long as nothing happens to me, there will eventually be a proper conclusion to the Raptormaniacs comic. It might take months or (more realistically?) years before I get to work on it, but it will be done. I am all too familiar with the frustration of following an enjoyable web series that fades away without notice to let that be the eternal fate of one of my own major works.

Speaking of how web series end, last year my friend Joan Turmelle and I made the difficult decision to officially cancel one of our longstanding and very popular collaborations, the webcomic TetZoo Time. However, in its place we have started a new paleontology-themed comic, Chile & Yi, which can be followed on DeviantArt and Tumblr. I consider Chile & Yi in some ways to be a spiritual successor to both TetZoo Time and Raptormaniacs, so if anyone is somehow starved for the very niche genre of "paleontology webcomics I am involved with", I encourage them to check it out.

The first comic we made for Chile & Yi.

I made a few significant changes to this blog proper as well, namely retiring two of my few annual Raptormaniacs traditions: the April Fools' posts (by choice) and the favorite new maniraptor polls (by necessity). Dispensing with the April Fools' posts in particular was another tough choice to make and I share the disappointment that some of my friends and readers have expressed in response, but I do think it was the right decision in the end. I have been considering alternative ways of celebrating the occasion in coming years though, so stay tuned! On the whole, it can be said that 2018 was a time of change for Raptormaniacs, despite the reduced posting frequency.

National Geographic called 2018 the Year of the Bird, and as usual scientific advances in our understanding of maniraptors continued unabated. In January, the structure of super-black bird-of-paradise feathers was described. Emperor penguins were reported feeding at night during breeding period. Structures in the lower jaw of caenagnathids were interpreted as vestigial tooth sockets. Stress in female yellow-legged gulls was found to prime their young for quicker antipredator behavior. Alarm calls were shown to evoke a visual search image for predators in Japanese tits. A new specimen of Archaeopteryx and an amber-trapped juvenile enantiornithine were described. New studies came out on the morphometrics of hesperornithines in comparison to extant diving birds, the kinematics of avian take-off, variation in growth patterns of basal paravians, the evolution of song in ovenbirds, the development of flight feathers, the diversification of fluvicoline flycatchers, the benefits of tool use in New Caledonian crows, the anatomy of finger joints in ostriches, and the importance of spatial memory for long-billed hermits. Newly-named maniraptors included the anchiornithid Caihong juji, the Miocene passerine Kischinskinia scandens, and the Cretaceous euornithine Eogranivora edentulata.

Holotype of Caihong juji, from Hu et al. (2018).

In February, a three-legged African penguin was reported. Tau accumulations (usually indicative of brain damage in humans) were documented in woodpeckers. New specimens of Anchiornis were described. Cognitive performance was shown to be linked to group size in Australian magpies. The ecology of New Zealand birds was inferred from coprolites. Yellow-billed oxpeckers were observed roosting on their mammalian hosts. It was argued that pelvic morphology prevented most Mesozoic avialans from sitting directly on their eggs. New studies came out on the adjustment of heart rate and body temperature in greylag geese, maneuverability in hummingbirds, thermoregulation in parrots, the distribution of medullary bone in birds, mimicry of hairy woodpeckers by downy woodpeckers, the evolution of drumming in woodpeckers, the biomechanics of terrestrial locomotion in birds, the taxonomic composition of vegaviids, the flight style of Concornis and Eoalulavis, the correlation between curvature and keratin sheath extent in beaks, the phylogenetic position of the Cuban macaw, and phalangeal joint kinematics of ostriches running on sand. Newly-named maniraptors included the Paleocene penguins Sequiwaimanu rosieae and Muriwaimanu tuatahi (formerly a species of Waimanu), the Miocene rails Litorallus livezeyi and Priscaweka parvales, the Miocene duck Chenoanas asiatica, and the southern dark newtonia (Newtonia lavarambo).

Downy woodpecker, photographed by Wolfgang Wander, under CC BY-SA 3.0.

In March, evidence of salt glands was reported in Iteravis. Black jacobins were found to vocalize above the known hearing range of birds. Genomic evidence of speciation reversal was documented in common ravens. A juvenile enantiornithine specimen was described. The diet of Mesozoic avialans was reviewed. Wing bone geometry in Archaeopteryx was put forth as evidence that it performed powered flight. The white-chested tinkerbird was shown to have been based on an individual of the yellow‐rumped tinkerbird. New studies came out on variation in avian egg shape and nest structure, the phylogeny of tytonid owls, call recognition in common cuckoos, the postcranial skeletal anatomy of Buitreraptor, cognitive deficiencies in hybrid chickadees, and the nanostructure of the avian eggshell. Newly-named maniraptors included the alvarezsaur Qiupanykus zhangi, the oviraptorosaur Anomalipes zhaoi, and the Oligocene heron Proardea deschutteri.

The skull of Iteravis, with a close-up highlighting the depressions that would have made space for salt glands, from Wang et al. (2018).

In April, the courtship display of the Vogelkop superb bird-of-paradise was released on film for the first time. The cranial anatomy of Confuciusornis was reevaluated. Teeth were found to represent a negligible proportion of body mass in avialans. Multiple parallel deinonychosaur trackways from the Tianjialou Formation and a new specimen of Citipati were described. Cowbird eggshells were shown to be more resistant to cracking than those of their hosts. Moa were discovered to not have dispersed large seeds. Madrynornis was redescribed. New studies came out on color polymorphism in owls, the phylogeny of neoavians, drivers of dwarfism in emus, the diversification of ovenbirds, the evolution of display complexity in birds-of-paradise, the benefits of high-speed stooping in peregrine falcons, the courtship display of Costa's hummingbirds, host suitability for common cuckoos, the morphometrics of accipitrid skull shape, the feeding mechanics of paravians (and other theropods), and the genome of the common loon. Newly-named maniraptors included the Pleistocene rail Rallus gracilipes.

The courtship display of the greater superb bird-of-paradise (A) compared to that of the Vogelkop superb bird-of-paradise (B), from Scholes and Laman (2018).

In May, deforestation was suggested to have contributed to differential survival in avialans during the K-Pg. A complete skull of Ichthyornis was described. Caller characteristics were found to influence recruitment to jackdaw mobs. Oviraptorosaurs were shown to have constructed their nests so that they could brood their eggs without crushing them. Incipient speciation and bony head protrusions in birds were reviewed. Hulsanpes was redescribed. The taxonomy of confuciusornithiforms was revised. New studies came out on migration to molting grounds in North American birds, the evolutionary assembly of the avian body plan, the biogeographic origins of Darwin's finches, the evolution of nesting characteristics in birds, visual fields in raptorial birds, the scaling of avian bipedal locomotion, feather development in ducks, skin ultrastructure of maniraptors, and the correlation between drumming behavior and genes that encode calcium-handling proteins in woodpeckers. Newly-named maniraptors included the Pliocene plover Vanellus liffyae and the Miocene galliform Panraogallus hezhengensis. The Ascent of Birds by John Reilly was published and my review of it can be found here.

Reconstructed skull of Ichthyornis, from Field et al. (2018).

In June, the evolution of tongue mobility in avialans (and other ornithodirans) was investigated. Cultural evolution in birds was reviewed. Age at fledging is found to be a cause and consequence of predation risk in passerines. Great tits were shown to have a high level of self control. New studies came out on high altitude colonization in ruddy ducks, nestling recognition in large-billed gerygones, genomic differentiation between northern flicker taxa, the taphonomy of submerged avian carcasses, the phylogeny of Antilophia and Chiroxiphia manakins, the ontogeny of the avian tail, the cranial morphology of Sinovenator, the evolution of vocal mimicry in songbirds, the phylogenetic position of Foro, and cultural transmission in New Caledonian crows. Newly-named maniraptors included the zygodactylid Zygodactylus grandei, the western square-tailed drongo (Dicrurus occidentalis), and the Whenua Hou diving petrel (Pelecanoides whenuahouensis).

Holotype of Zygodactylus grandei, from Smith et al. (2018).

In July, the spectacled cormorant was shown to have formerly lived in Japan. Coordinated misdirection was reported to be a widespread anti-predator behavior in Neotropical birds. Preserved eggshell cuticle in Cretaceous maniraptors was examined. Tactile interactions between American crows and dead conspecifics were documented. The development of avian digits was reviewed. New studies came out on the structure of parrot brains, egg size in Oriental cuckoos, aggressive interactions between crows and ravens, the phylogeny of Chaetura swifts, the agility of running birds, the visual displays of Costa's hummingbirds, the morphology of avian maxillae, the forelimb musculature of African gray parrots, the middle ear vasculature of passerines, the relationship between avian egg shape and rolling dynamics, the dynamics of take-off and landing in diamond doves, and the basicranial soft tissues of Nothronychus. Newly-named maniraptors included the Miocene passerine Cinclosoma elachum and the Oligocene osprey Pandion pannonicus.

Schematic of coordinated misdirection performed by a pair of yellow-throated euphonias, showing the female discreetly entering their nest as the male continues to fly onward, diverting the attention of observers away from the location of the nest, from Gulson-Castillo et al. (2018).

In August, the genome of the ʻalalā was assembled. Categorical perception of color was reported in zebra finches. Economic decision-making was found in parrots. New studies came out on heterospecific alarm call recognition in superb fairy-wrens, signatures of human commensalism in the house sparrow genome, the endocranial anatomy of oviraptorosaurs, the evolution of egg shape in birds, swimming kinematics in common loons, the incubation period of troodonts, facial display in blue-and-yellow macaws, the development of pelagornithid pseudoteeth, long-range dispersal in tawaki, color vision in Harris's hawks, and colonization of habitat patches by willow warblers. Newly-named maniraptors included the confuciusornithiform Yangavis confucii, the Oligocene passerine Winnicavis gorskii, and the alvarezsaurs Bannykus wulatensis and Xiyunykus pengi.

Select bones and reconstructed skeletal of Bannykus wulatensis, from Xu et al. (2018).

In September, preserved pellets were described in Anchiornis. Reflection of near-infrared light was found to be a thermoregulatory strategy used by birds. Ejecting parasitic cowbird eggs was shown to be costly for dickcissels. New studies came out on the killing kinematics of loggerhead shrikes, the visual attention of pigeons, genomic differentiation in recently-diverged avian species, molting patterns in gruiforms, the evolution of parental activity at the nest in birds, the preservation of Shuvuuia feathers, the abundance and survival of migratory birds in North America, the development of striped feathers in galliforms, and adaptations for having proportionately large brains in hummingbirds. Newly-named maniraptors included the basal pygostylian Jinguofortis perplexus, the elephant bird Vorombe titan, and the blue-throated hillstar (Oreotrochilus cyanolaemus).

Anchiornis specimen preserved with pellet, from Zheng et al. (2018).

In October, pigmented dinosaur eggshells were found to likely have originated among maniraptors. Patterns of diversification in the avian limb skeleton were shown to be correlated with clade-specific ontogenetic trajectories. A new specimen of Archaeorhynchus with preserved lungs was described. New Caledonian crows were reported to be capable of constructing compound tools. Rapid speciation in manakins was suggested to be linked to acrobatic courtship behavior. The sensory ecology of elephant birds was investigated based on endocranial anatomy, though inferences of nocturnality are likely premature. New studies came out on pair bonding in great tits, the courtship display of blue-capped cordon-bleus, the genetic basis for color polymorphism in Gouldian finches, song learning in savannah sparrows, the evolution of iris color in owls and signal modality in birds, the mitochondrial genomes of parrots, the phylogenetic position of Mascarene owls, the phylogeny of babblers, the origin of the Inaccessible Island rail, the diversification of Todiramphus kingfishers, near-ground soaring in Gyps vultures, heat-conservation behaviors in birds, the correlation between avian pelvis and egg size, the ontogeny of wing-assisted incline running, the senses used by scavenging birds, the taxonomy of the white-browed shortwing, and stability during avian take-off. Newly-named maniraptors included the basal avialan Archaeopteryx albersdoerferi, the enantiornithine Orienantius ritteri, and the Rote leaf warbler (Phylloscopus rotiensis).

The evolution of eggshell pigmentation mapped onto archosaur phylogeny, from Wiemann et al. (2018).

In November, the crest feathers of peafowl were shown to be attuned to frequencies generated by their courtship displays. A three-species hybrid wood-warbler was reported. The textbook wisdom that the black bib of house sparrows signals dominance was questioned. The molecular and cellular profiles of avian scales were shown to be distinct from those of crocodylian scales. The smallest known dromaeosaurid tracks were described. New studies came out on plumage patterns of Confuciusornis, tool making in Goffin's cockatoos, gliding strategies in Gyps vultures, the evolution of iridescent plumage, fuel load in birds, the biomechanics of foraging flight in common swifts, the genetic basis for bill size in black-bellied seedcrackers, correlated complexity in the displays of birds-of-paradise, and the phylogeny of Hylopezus and Myrmothera antpittas. Newly-named maniraptors included the enantiornithines Mirarce eatoni and Gettyia gloriae (formerly a species of Avisaurus).

The suggested formation of a three-species hybrid wood-warbler (pictured in C), from Toews et al. (2018).

In December, amber-trapped specimens of rachis-dominated feathers were described. Medullary bone was reported in an enantiornithine. Hybrid speciation in birds was reviewed. A nesting rufous-tailed hummingbird was documented mistakenly attacking a snake-mimicking caterpillar. Secondary flightlessness was shown not to correlate with brain morphology in neornithines. Aerodynamic forces produced by the wings of Caudipteryx were found to have been limited. New studies came out on different rates of ageing between different white-throated sparrow morphs, the genomic basis for increased cognition and longevity in parrots, the structure of primary feathers, the evolutionary links between different signaling traits in hummingbirds, the relationship between beak shape and feeding ecology in birds, population differentiation in northern cardinals, the development of avian forelimb position, the courtship display of broad-tailed hummingbirds, and the phylogenetic affinities of Calcardea. Newly-named maniraptors included the recently extinct pigeon Ducula tihonireasini.

Rachis-dominated feathers preserved in amber, from Xing et al. (2018).

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