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Re: [dinosaur] Pennaraptoran theropod dinosaurs (new monograph) (free pdf)



Press release:


A volume on past progress and new frontiers in the study of early birds and their close relatives


https://hku.hk/press/news_detail_21459.html


https://phys.org/news/2020-08-volume-frontiers-early-birds-relatives.html

Virus-free. www.avg.com

On Sun, Aug 23, 2020 at 12:32 PM Ben Creisler <bcreisler@gmail.com> wrote:

Ben Creisler
bcreisler@gmail.com

For the record and to help online searches find DML archive content, here are the individual chapters with pdfs and abstracts:



Section 1. Systematics, fossil record, and biogeography
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Michael Pittman, Jingmai OâConnor, Daniel J. Field, Alan H. Turner, Waisum Ma, Peter Makovicky, and Xing Xu (2020)
Chapter 1. Pennaraptoran systematics
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 7-36
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-01-pittman_et_al.pdf

New and important pennaraptoran specimens continue to be discovered on a regular basis. Yet, with these discoveries the number of viable phylogenetic hypotheses has increased, including ones that challenge the traditional grouping of dromaeosaurids and troodontids within a monophyletic Deinonychosauria. This chapter will cover recent efforts to address prevailing phylogenetic uncertainties and controversies, both between and within key clades, including deinonychosaurian monophyly, the phylogenetic position of anchiornithines and scansoriopterygids, and the interrelationships of enantiornithines. While recent discoveries mainly from Asia have created much of the latest uncertainty and controversy, new material, particularly from Asia, promises to rather fittingly address these issues. Further curatorship of long-standing phylogenetic datasets and more prevalent use of extended analytical protocols will be essential to meeting this challenge, especially for groups whose boundaries have been blurred. As it becomes increasingly difficult to study all fossil materials, owing to their growing numbers and ever disparate locations, broader use of digital fossils and online character databases for character coding is acutely needed to ensure that errors arising from remote, rather than firsthand, scoring are reduced as far as possible, particularly at this time of rapid data accumulation.

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Michael Pittman, Jingmai OâConnor, Edison Tse, Peter Makovicky, Daniel J. Field, Waisum Ma, Alan H. Turner, Mark A. Norell, Rui Pei, and Xing Xu (2020)
Chapter 2. The fossil record of Mesozoic and Paleocene pennaraptorans
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 37-95
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-02-pittman_et_al.pdf

An unabated surge of new and important discoveries continues to transform knowledge of pennaraptoran biology and evolution amassed over the last 150+ years. This chapter summarizes progress made thus far in sampling the pennaraptoran fossil record of the Mesozoic and Paleocene and proposes priority areas of attention moving forward.
Oviraptorosaurians are bizarre, nonparavian pennaraptorans first discovered in North America and Mongolia within Late Cretaceous rocks in the early 20th century. We now know that oviraptorosaurians also occupied the Early Cretaceous and their unquestionable fossil record is currently limited to Laurasia. Early Cretaceous material from China preserves feathers and other soft tissues and ingested remains including gastroliths and other stomach contents, while brooding specimens and age-structured, single-species accumulations from China and Mongolia provide spectacular behavioral insights. Less specialized early oviraptorosaurians like Incisivosaurus and Microvenator remain rare, and ancestral forms expected in the Late Jurassic are yet to be discovered, although some authors have suggested Epidexipteryx and possibly other scansoriopterygids may represent early-diverging oviraptorosaurians.

Long-armed scansoriopterygids from the Middle-Late Jurassic of Laurasia are either early-diverging oviraptorosaurians or paravians, and some have considered them to be early-diverging avialans. Known from five (or possibly six) feathered specimens from China, only two mature individuals exist, representing these taxa. These taxa, Yi and Ambopteryx, preserve stylopod-supported wing membranes that are the only known alternative to the feathered, muscular wings that had been exclusively associated with dinosaurian flight. Thus, scansoriopterygid specimensâparticularly those preserving soft tissueâremain a key priority for future specimen collection.

Dromaeosaurids and troodontids were first discovered in North America and Mongolia in Late Cretaceous rocks. More recent discoveries show that these animals originated in the Late Jurassic, were strikingly feathered, lived across diverse climes and environments, and at least in the case of dromaeosaurids, attained a global distribution and the potential for aerial locomotion at small size.China and Mongolia have yielded the most dromaeosaurid and troodontid specimens and taxa, but Gondwanan troodontids are almost unknown compared to southern dromaeosaurids, so the fidelity of this biogeographical signal is worth further exploration. Discovery of well-preserved Middle-Late Jurassic material will be crucial for understanding the origin of key dromaeosaurid and troodontid traits, with the controversial anchiornithines potentially already offering this if their troodontid status can be solidified.

In line with the preferences of most theropod palaeontologists, birds are defined herein as members of Avialae, including stem and crown taxa, whilst Aves herein refers to crown-group birds (see Pittman et al., chapter 1, for the precise definition of Avialae adopted; elsewhere, typically among ornithologists, Aves refers to stem and crown taxa whilst Neornithes refers to crown-group birds). Despite taphonomic bias against avialans in the fossil record, their Early Cretaceous record is fairly robust largely due to the high taxonomic and ecological diversity preserved within the rich Jehol deposits of northeastern China. Archaeopteryx (and possibly the controversial Middle-Late Jurassic anchiornithines) show what some of the earliest birds were like, but better-preserved soft tissues hold the key to understanding their substantially different anatomy and flight capabilities to crown-group birds (Aves).

The Late Cretaceousâearly Paleocene fossil record of crown birds is especially poor, and improved sampling will be necessary to clarify our understanding of avialan survivorship, ecological selectivity, and recovery across the end-Cretaceous mass extinction. Deposits of Eocene age, such as Messel and Green River, have been especially useful for documenting the early evolutionary history of crown birds. However, the discovery of new Cretaceous and/or Palaeogene bird-bearing lagerstÃtten from Gondwana will be important for accurately determining ancestral biogeographic patterns.

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Diego Pol and Pablo A. Goloboff (2020)
Chapter 3. The impact of unstable taxa in coelurosaurian phylogeny and resampling support measures for parsimony analyses
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 97-115
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-03-pol_goloboff.pdf

Paleontological datasets often have large amounts of missing entries that result in multiple most parsimonious trees. Highly incomplete and conflictive taxa produce a collapsed strict consensus and several methods have been developed for identifying these unstable or rogue taxa in optimal trees derived from phylogenetic analyses. In addition to decreasing consensus resolution, incomplete or conflictive taxa can also severely affect the support values of phylogenetic analysis in paleontological datasets. Here, we explore a protocol for the identification of taxa that decrease jackknife support values in parsimony analysis. The taxa identified are excluded from majority rule jackknife trees, revealing nodes that have either low or high support irrespective of the uncertainties in the placement of unstable taxa. A recently published dataset of coelurosaurian relationships based on 164 taxa and 853 characters is explored using this protocol; our protocol detects a total of 40 unstable taxa as the most detrimental for node supports. Major clades that are well supported in the reduced jackknife tree include Coelurosauria, Maniraptoriformes, Compsognathidae, Ornithomimosauria, Alvarezsauroidea, Therizinosauria, Oviraptorosauria. Clades with moderate support instead include Maniraptora, Pennaraptora, Paraves, Dromaeosauridae, Troodontidae, Anchiornithinae, and early-diverging clades of Avialae.

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Anyang Ding, Michael Pittman, Paul Upchurch, Jingmai OâConnor, Daniel J. Field, and Xing Xu (2020)
Chapter 4. The biogeography of coelurosaurian theropods and its impact on their evolutionary history
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 117-157
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-04-ding_et_al.pdf

The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earthâs surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately, few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the Theropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentation-induced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges.

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Daniel J. Field, Jacob S. Berv, Allison Y. Hsiang, Robert Lanfear, Michael J. Landis, and Alex Dornburg (2020)
Chapter 5. Timing the extant avian radiation : the rise of modern birds, and the importance of modeling molecular rate variation
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 159-181
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-05-field_et_al.pdf

Unravelling the phylogenetic relationships among the major groups of living birds has been described as the greatest outstanding problem in dinosaur systematics. Recent work has identified portions of the avian tree of life that are particularly challenging to reconstruct, perhaps as a result of rapid cladogenesis early in crown bird evolutionary history (specifically, the interval immediately following the end-Cretaceous mass extinction). At face value this hypothesis enjoys support from the crown bird fossil record, which documents the first appearances of most major crown bird lineages in the early Cenozoicâin line with a model of rapid postextinction niche-filling among surviving avian lineages. However, molecular-clock analyses have yielded strikingly variable estimates for the age of crown birds, and conflicting inferences on the impact of the end-Cretaceous mass extinction on the extant bird radiation. This uncertainty has often been ascribed to a patchy avian fossil record, but the possibility of model misspecification in molecular divergence-time analyses represents an important and relatively underexplored alternative hypothesis. Here, we highlight the necessity of further developing and using models that account for coordinated variation in rates of molecular evolution across a phylogeny (e.g., molecular early burst) as a means of assessing support for a rapid post-Cretaceous radiation of crown birds. We discuss how relationships between life history and substitution rates can mislead divergence-time studies that do not account for directional changes in substitution rates over time, and suggest that these effects might have caused some of the variation in existing molecular date estimates for birds. We suggest multiple paths forward that could help resolve this and similar conflicts within other major eukaryotic clades.

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Section 2. Anatomical frontiers

Sergio M. Nebreda, Guillermo NavalÃn, Iris MenÃndez, Trond Sigurdsen, Luis M. Chiappe, and JesÃs MarugÃn-LobÃn (2020)
Chapter 6. Disparity and macroevolutionary transformation of the maniraptoran manus
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 183-203
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-06-nebreda_et_al.pdf

Multiple factors involved in the evolutionary transformation of the manus across the maniraptoran radiation, including its current morphology in modern birds, remain unexplored. Specifically, the morphological disparity of the manus has never been studied quantitatively, and there are no hypotheses about the possible mechanisms and constraints underlying its evolution. Morphological disparity is best studied with shape-analysis tools based on Procrustes methods, because they guarantee the independence of shape from size while depicting the results in expressive graphics. However, this methodology compares fixed configurations of coordinates, preventing their use in highly articulated and movable structures such as the maniraptoran manus. Here, we propose a new protocol, the one-dimensional Procrustes analysis (OPA), for transforming the chord lengths of these bones into unidimensional Cartesian coordinates, enabling treatment of the data under the operational advantages of the Procrustes methods. Our results applying this new method on a sample encompassing 174 maniraptoran dinosaurs manus, including 79 fossils (both avialan and nonavialan taxa) and 95 extant paleognathans and neognathans, document the morphological transition between early-diverging maniraptorans, nonavialan paravians, and birds over morphospace, highlighting an unexpectedly low disparity in the crown group when compared to early-diverging taxa. Within this transition, we show a common trend of proportional reduction and loss of distal elements, mostly in the minor and alular digits. Furthermore, our study reveals an allometric pattern characterizing manus morphological variation between early-diverging maniraptorans and enantiornithine avialans that disappears in crown birds and their closest early-diverging counterparts. This previously unnoticed allometric trend suggests a complex interplay of developmental, functional, and historical constraints in the evolution of the maniraptoran manus.

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Shuo Wang, Josef Stiegler, Ping Wu, and Cheng-ming Chuong (2020)
Chapter 7. Tooth vs. beak : the evolutionary developmental control of the avian feeding apparatus
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 205-228
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-07-wang_et_al.pdf

Recent discoveries of exquisitely preserved nonavialan and avialan theropod dinosaurs have not only prompted studies of theropod tooth morphologies, but have also provided information about the origin and early evolution of avian beaks. Recent studies on beak morphologies and morphogenesis in Darwinâs finches have greatly improved our understanding of how avian beaks adapt to various ecological niches, but the question of how birds lost their teeth during the course of evolution has long been debated. Evolutionary developmental experiments performed on extant bird embryos bridge the gap between paleontological and neontological evidence, suggesting that the avian beak could have originated through heterochronic truncation of odontogenesis over evolutionary time. Here, we systematically review independently evolved regional and complete edentulism present in nonavialan and avialan theropod dinosaurs, and suggest that the tooth-reduction processes of different jaw bones are likely to be independently controlled. Through reviewing the recent advances of molecular regulations involved in tooth and avian beak morphogenic processes, we suggest that several molecules regulating the development of the avian beak also mediate the growth of keratinous rhamphothecae, and the divergence of odontogenic signalling pathways are likely to have accounted for both of these processes.


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Waisum Ma, Michael Pittman, Stephan Lautenschlager, Luke E. Meade, and Xing Xu (2020)
Chapter 8. Functional morphology of the oviraptorosaurian and scansoriopterygid skull Â
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 29-249
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-08-ma_et_al.pdf

Oviraptorosauria and Scansoriopterygidae are theropod clades that include members suggested to have partially or fully herbivorous diets. Obligate herbivory and carnivory are two ends of the spectrum of dietary habits along which it is unclear how diet within these two clades might have varied. Clarifying their diet is important as it helps understanding of dietary evolution close to the dinosaur-bird transition. Here, diets are investigated by conventional comparative anatomy, as well as measuring mandibular characteristics that are plausibly indicative of the animalâs feeding habit, with reference to modern herbivores that may also have nonherbivorous ancestry. In general, the skulls of scansoriopterygids appear less adapted to herbivory compared with those of oviraptorids because they have a lower dorsoventral height, a smaller lateral temporal fenestra, and a smaller jaw-closing mechanical advantage and they lack a tall coronoid process prominence. The results show that oviraptorid mandibles are more adapted to herbivory than those of caenagnathids, earlydiverging oviraptorosaurians and scansoriopterygids. It is notable that some caenagnathids possess features like an extremely small articular offset, and low average mandibular height may imply a more carnivorous diet than the higher ones of other oviraptorosaurians. Our study provides a new perspective to evaluate different hypotheses on the diets of scansoriopterygids and oviraptorosaurians, and demonstrates the high dietary complexity among early-diverging pennaraptorans.

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Arindam Roy, Christopher S. Rogers, Thomas Clements, Michael Pittman, Olivier Habimana, Peter Martin, and Jakob Vinther (2020)
Chapter 9. Fossil microbodies are melanosomes : evaluating and rejecting the 'fossilised decay-associated microbes' hypothesisÂ
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 251-276
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-09-roy_et_al.pdf

Melanosomes are membrane-bound organelles of varying geometry, commonly found within a range of vertebrate tissues, that contain the pigment melanin. Melanosomes have been identified in the fossil record in many exceptionally preserved fossils allowing reconstructions of the coloration of many extinct animals. However, these microstructures have also been interpreted as âmicrobial cellsâ or melanin-producing bacteria based on their geometric similarities to melanosomes. Here we test these two conflicting hypotheses experimentally. Our results demonstrate multiple lines of evidence that these fossil microbodies are indeed melanosomes: the geometry of decay-associated microbes differs significantly from fossil microbodies; fossil microbodies are very strongly localized to in vivo melanized tissues and are absent in tissues typically unmelanized in vivo, in all fossils examined regardless of lithology or age.
On the basis of these results, as well as a thorough review of existing literature on melaninlike pigments, we are able to rule out a bacterial origin for fossil microbodies associated with exceptional vertebrate fossils and demonstrate that fossil microbodies are in fact preserved melanosomes.


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Section 3. Early-flight study : methods, status, and frontiers
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Michael Pittman, Ashley M. Heers, Francisco J. Serrano, Daniel J. Field, Michael B. Habib, T. Alexander Dececchi, Thomas G. Kaye, and Hans C.E. Larsson (2020)
Chapter 10. Methods of studying early theropod flight
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 277-294
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-10-pittman_et_al.pdf

The study of early theropod flight involves avialans as well as other pennaraptorans. It requires the study of anatomy that is familiar to the modern ornithologist, but also very different and alien. Early theropod flight therefore necessitates study methods that can incorporate what we know about sophisticated powered and unpowered flight in living birds while being mindful of the differences between them and the earliest theropod flyers. In this chapter we will survey key methods and approaches, covering their best-practice applications along the timeline of early theropod flight evolution and priorities for future method development.


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T. Alexander Dececchi, Hans C.E. Larsson, Michael Pittman, and Michael B. Habib (2020)
Chapter 11. High flyer or high fashion? A comparison of flight potential among small-bodied paravians
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 295-320
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-11-dececchi_et_al.pdf

The origin of flight in birds and its relationship to bird origins itself has achieved something of a renaissance in recent years, driven by the discovery of a suite of small-bodied taxa with large pennaceous feathers. As some of these specimens date back to the Middle Jurassic and predate the earliest known birds, understanding how these potential aerofoil surfaces were used is of great importance to answering the question: which came first, the bird or the wing? Here we seek to address this question by directly comparing key members of three of the major clades of paravians: anchiornithines, Microraptor and Archaeopteryx across their known size classes to see how they differ in terms of major flight-related parameters (wing loading; disc loading; specific lift; glide speed; takeoff potential). Using specimens with snout to vent length (SVL) ranging from around 150 mm to 400 mm and mass ranging from approximately 130 g to 2 kg, we investigated patterns of inter- and intraspecific changes in flight potential. We find that anchiornithines show much higher wing- and discloading values and correspondingly high required minimum glide and takeoff speeds, along with lower specific lift and flapping running outputs suggesting little to no flight capability in this clade. In contrast, we see good support for flight potential, either gliding or powered flight, for all size classes of both Microraptor and Archaeopteryx, though there are differing patterns of how this shifts ontogenetically. These findings, coupled with previous findings of a lack of wing-based locomotion in early-diverging troodontids or dromaeosaurids, suggest that flight was not a synapomorphy of Paraves. This supports the contention that flight capacity and potentially powered flight itself arose convergently in at least two distinct paravian lineages, first in birds minimally 150 million years ago, then in the microraptorines 20â30 million years later. Our work indicates that the origin of flight among paravians was likely a more complex phenomenon than previously appreciated.


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Hans C.E. Larsson, Michael B. Habib, and T. Alexander Dececchi (2020)
Chapter 12. Navigating functional landscapes : a birdâs eye view of the evolution of avialan flight
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 321-332
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-12-larsson_et_al.pdf

One of the major challenges in attempting to parse the ecological setting for the origin of flight in Pennaraptora is determining the minimal fluid and solid biomechanical limits of gliding and powered flight present in extant forms and how these minima can be inferred from the fossil record. This is most evident when we consider the fact that the flight apparatus in extant birds is a highly integrated system with redundancies and safety factors to permit robust performance even if one or more components of their flight system are outside their optimal range. These subsystem outliers may be due to other adaptive roles, ontogenetic trajectories, or injuries that are accommodated by a robust flight system. This means that many metrics commonly used to evaluate flight ability in extant birds are likely not going to be precise in delineating flight style, ability, and usage when applied to transitional taxa. Here we build upon existing work to create a functional landscape for flight behavior based on extant observations. The functional landscape is like an evolutionary adaptive landscape in predicting where estimated biomechanically relevant values produce functional repertoires on the landscape. The landscape provides a quantitative evaluation of biomechanical optima, thus facilitating the testing of hypotheses for the origins of complex biomechanical functions. Here we develop this model to explore the functional capabilities of the earliest known avialans and their sister taxa. This mapping allows us to determine where they are placed on the landscape and how phylogenetic trends may course over the landscape. Moreover, the mapping develops a novel tool for assessing potential selection pressures and directions using the quantitative tools developed for adaptive landscapes. Combining these findings with previous work on the ontogeny of the flight stroke, especially in chukar partridges, allows us to test whether this widely used proxy is really suitable and whether we can use ontogenetic trajectories for reconstructing the evolutionary trajectory of the nonavialan theropod to bird transition.

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Francisco J. Serrano, Michael Pittman, Thomas G. Kaye, Xiaoli Wang, Xiaoting Zheng, and Luis M. Chiappe (2020)
Chapter 13. Laser-stimulated fluorescence refines flight modeling of the Early Cretaceous bird Sapeornis
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 334-344
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-13-serrano_et_al.pdf

Unseen and difficult-to-see soft tissues of fossil birds revealed by laser-stimulated fluorescence (LSF) shed light on their functional morphology. Here we study a well-preserved specimen of the early pygostylian Sapeornis chaoyangensis under LSF and use the newly observed soft-tissue data to refine previous modeling of its aerial performance and to test its proposed thermal soaring capabiliÂties. Under LSF, the bodyâs lateral outline is observed, permitting direct estimates of the bodyâs disc surface that generates drag during flight (Sb). This surface and the body drag coefficientâwhich is better estimated knowing Sbâ are influential parameters in modeling flight dynamics. In particular, we focus on two aspects of flight dynamics: the calculation of the power margin during flapping flight (power curve), and the sinking speed during gliding (glide polar). Results from revised models using our direct soft-tissue measurements support the notion that Sapeornis was a thermal soarer that glided for long periods. LSF also confirms the absence of a true alula in Sapeornis. While the deployment of the alular digit could have enhanced control during slow flight, the position of this digit along the handwing (distal part of the wing) suggests limited maneuverability. This study demÂonstrates how soft-tissue preservation can be incorporated into modeling of flight dynamics in light of ever-improving palaeontological imaging techniques.

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Fernando E. Novas, Federico L. AgnolÃn, Federico Brisson Egli, and GastÃn E. Lo Coco (2020)
Chapter 14. Pectoral girdle morphology in early-diverging paravians and living ratites : implications for the origin of flight
In Michael Pittman & Xing Xu, editors, Pennaraptoran Theropod Dinosaurs : Past Progress and New Frontiers
Bulletin of the American Museum of Natural History 440(1): 345-353
http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-14-novas_et_al.pdf

Discussions about the origin of flight almost unanimously assume that early birds positioned (and moved) their wings in the same basic manner as living flying birds, with reconstructed wings extended with the airfoil surface parallel to the ground and forelimbs moving in a dorsoventral arc. Such reconstructions of wing posture and movements for extinct avialans are based on highly specialized flying neognaths, in which the glenoid cavity is horizontally extended and laterodorsally faced, thus allowing wide humeral rotation and increased upward excursion. However, living ratites exhibit a sharply different pattern of pectoral girdle (or shoulder girdle) morphology and associated wing movements: in both Rhea and Struthio the glenoid cavity faces laterally, but its major axis is almost vertical. In consequence, wings predominantly move following an anterolateral to posteromedial abduction-adduction arc. Initial experimental results with Rhea americana demonstrate their inability to perform WAIR (wing-assisted incline running), suggesting a causal relationship between the inability to flap the wings vigorously and its pectoral girdle morphology (with glenoid cavity subvertically oriented, poorly developed acrocoracoid process, and m. supracoracoideus playing a protractor rather than elevator function). Early-diverging paravians (e.g., Saurornitholestes, Buitreraptor, Microraptor) and early-diverging birds (e.g., Archaeopteryx, Anchiornis) share a closely similar morphology of scapula and coracoid, with a glenoid cavity facing laterally and with its greater axis oriented subvertically. This condition of the glenoid resembles that of ratites, allowing one to infer that fully extended wings of early-diverging paravians (including Archaeopteryx) oriented their surface obliquely to the ground. Experimental results, in conjunction with anatomical observations in both flying and flightless living birds, warn about the purported generalized ability of early-diverging paravians to perform WAIR. Even if they were capable of symmetrical flapping, their wing movements were different from those of living neognaths, because the glenoid retained both a plesiomorphic morphology and orientation. Wing strokes as hypothesized here for early-diverging paravians may have generated thrust with little or no lift. WAIR behavior was present in the common ancestor of Neognathae, and also probably present in early-diverging ornithothoracines. However, WAIR performance among early-diverging paravians and early birds remains uncertain. In agreement with recent contributions, we conclude that the origin of flapping flight (and eventually WAIR) emerged in birds that diverged later than Archaeopteryx, with the acquisition of a horizontally placed major glenoid axis, which allowed wider dorsoventral forelimb excursions.


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On Fri, Aug 21, 2020 at 8:57 AM Ben Creisler <bcreisler@gmail.com> wrote:
Ben Creisler

A new monograph on pennaraptoran theropods as a Bulletin of the American Museum of Natural History is now available as a free pdf.Â

The supplementary stuff is posted and free on the AMNH site.ÂÂ



Pittman, Michael; Xu, Xing; O'Connor, Jingmai.; Field, Daniel J.; Turner, Alan H. (Alan Hamilton); Ma, Waisum.; Makovicky, Peter J.; Tse, Edison.; Norell, Mark.; Pei, Rui.; Pol, Diego.; Goloboff, Pablo A.; Ding, Anyang.; Upchurch, Paul.; Berv, Jacob S.; Hsiang, Allison Y.; Landis, Michael J.; Dornburg, Alex.; Nebreda, Sergio M.; NavalÃn, Guillermo.; MenÃndez, Iris.; Sigurdsen, Trond.; Chiappe, Luis M.; MarugÃn-LobÃn, JesÃs.; Wang, Shuo.; Stiegler, Josef.; Wu, Ping.; Zhong, Zhengming.; Lautenschlager, Stephan.; Meade, Luke E.; Roy, Arindam.; Rogers, Christopher S.; Clements, Thomas.; Habimana, Olivier.; Martin, Peter.; Heers, Ashley M.; Serrano, Francisco J.; Habib, Michael B.; Dececchi, T. Alexander.; Kaye, Thomas G.; Larsson, Hans C.E.; Wang, Xiaoli.; Zheng, Xiaoting.; Novas, Fernando E.; AgnolÃn, Federico L.; Egli, Federico Brisson.; Lo Coco, GastÃn E. (2020)
Pennaraptoran theropod dinosaurs : past progress and new frontiers.
Bulletin of the American Museum of Natural History 440(1):1-355
doi: https://doi.org/10.1206/0003-0090.440.1.1
URI: http://digitallibrary.amnh.org/handle/2246/7237

https://bioone.org/journals/Bulletin-of-the-American-Museum-of-Natural-History/volume-440/issue-1/0003-0090.440.1.1/Pennaraptoran-Theropod-Dinosaurs-Past-Progress-and-New-Frontiers/10.1206/0003-0090.440.1.1.short


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Table of Contents:

Introduction / Michael Pittman and Xing Xu

Section 1. Systematics, fossil record, and biogeography

Chapter 1. Pennaraptoran systematics / Michael Pittman, Jingmai OâConnor, Daniel J. Field, Alan H. Turner, Waisum Ma, Peter Makovicky, and Xing Xu

Chapter 2. The fossil record of Mesozoic and Paleocene pennaraptorans / Michael Pittman, Jingmai OâConnor, Edison Tse, Peter Makovicky, Daniel J. Field, Waisum Ma, Alan H. Turner, Mark A. Norell, Rui Pei, and Xing Xu

Chapter 3. The impact of unstable taxa in coelurosaurian phylogeny and resampling support measures for parsimony analyses / Diego Pol and Pablo A. Goloboff

Chapter 4. The biogeography of coelurosaurian theropods and its impact on their evolutionary history / Anyang Ding, Michael Pittman, Paul Upchurch, Jingmai OâConnor, Daniel J. Field, and Xing Xu

Chapter 5. Timing the extant avian radiation : the rise of modern birds, and the importance of modeling molecular rate variation / Daniel J. Field, Jacob S. Berv, Allison Y. Hsiang, Robert Lanfear, Michael J. Landis, and Alex Dornburg --

Section 2. Anatomical frontiers

Chapter 6. Disparity and macroevolutionary transformation of the maniraptoran manus / Sergio M. Nebreda, Guillermo NavalÃn, Iris MenÃndez, Trond Sigurdsen, Luis M. Chiappe, and JesÃs MarugÃn-LobÃn

Chapter 7. Tooth vs. beak : the evolutionary developmental control of the avian feeding apparatus / Shuo Wang, Josef Stiegler, Ping Wu, and Cheng-ming Chuong

Chapter 8. Functional morphology of the oviraptorosaurian and scansoriopterygid skull / Waisum Ma, Michael Pittman, Stephan Lautenschlager, Luke E. Meade, and Xing Xu

Chapter 9. Fossil microbodies are melanosomes : evaluating and rejecting the âfossilised decay-associated microbesâ hypothesis / Arindam Roy, Christopher S. Rogers, Thomas Clements, Michael Pittman, Olivier Habimana, Peter Martin, and Jakob Vinther --

Section 3. Early-flight study : methods, status, and frontiers

Chapter 10. Methods of studying early theropod flight / Michael Pittman, Ashley M. Heers, Francisco J. Serrano, Daniel J. Field, Michael B. Habib, T. Alexander Dececchi, Thomas G. Kaye, and Hans C.E. Larsson

Chapter 11. High flyer or high fashion? A comparison of flight potential among small-bodied paravians / T. Alexander Dececchi, Hans C.E. Larsson, Michael Pittman, and Michael B. Habib

Chapter 12. Navigating functional landscapes : a birdâs eye view of the evolution of avialan flight / Hans C.E. Larsson, Michael B. Habib, and T. Alexander Dececchi

Chapter 13. Laser-stimulated fluorescence refines flight modeling of the Early Cretaceous bird Sapeornis / Francisco J. Serrano, Michael Pittman, Thomas G. Kaye, Xiaoli Wang, Xiaoting Zheng, and Luis M. Chiappe

Chapter 14. Pectoral girdle morphology in early-diverging paravians and living ratites : implications for the origin of flight / Fernando E. Novas, Federico L. AgnolÃn, Federico Brisson Egli, and GastÃn E. Lo Coco.


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Free pdfs:

Supplemental Material for 'Pennaraptoran theropod dinosaurs : past progress and new frontiers.
Bulletin of the American Museum of Natural History 440



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