Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique

Despite the ubiquity of raptors in terrestrial ecosystems, many aspects of their predatory behaviour remain poorly understood. Surprisingly little is known about the morphology of raptor talons and how they are employed during feeding behaviour. Talon size variation among digits can be used to distinguish families of raptors and is related to different techniques of prey restraint and immobilisation. The hypertrophied talons on digits (D) I and II in Accipitridae have evolved primarily to restrain large struggling prey while they are immobilised by dismemberment. Falconidae have only modest talons on each digit and only slightly enlarged D-I and II. For immobilisation, Falconini rely more strongly on strike impact and breaking the necks of their prey, having evolved a ‘tooth’ on the beak to aid in doing so. Pandionidae have enlarged, highly recurved talons on each digit, an adaptation for piscivory, convergently seen to a lesser extent in fishing eagles. Strigiformes bear enlarged talons with comparatively low curvature on each digit, part of a suite of adaptations to increase constriction efficiency by maximising grip strength, indicative of specialisation on small prey. Restraint and immobilisation strategy change as prey increase in size. Small prey are restrained by containment within the foot and immobilised by constriction and beak attacks. Large prey are restrained by pinning under the bodyweight of the raptor, maintaining grip with the talons, and immobilised by dismemberment (Accipitridae), or severing the spinal cord (Falconini). Within all raptors, physical attributes of the feet trade off against each other to attain great strength, but it is the variable means by which this is achieved that distinguishes them ecologically. Our findings show that interdigital talon morphology varies consistently among raptor families, and that this is directly correlative with variation in their typical prey capture and restraint strategy

The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds

Most non-avian theropod dinosaurs are characterized by fearsome serrated teeth and sharp recurved claws. Interpretation of theropod predatory ecology is typically based on functional morphological analysis of these and other physical features. The notorious hypertrophied ‘killing claw’ on pedal digit (D) II of the maniraptoran theropod Deinonychus (Paraves: Dromaeosauridae) is hypothesized to have been a predatory adaptation for slashing or climbing, leading to the suggestion that Deinonychus and other dromaeosaurids were cursorial predators specialized for actively attacking and killing prey several times larger than themselves. However, this hypothesis is problematic as extant animals that possess similarly hypertrophied claws do not use them to slash or climb up prey. Here we offer an alternative interpretation: that the hypertrophied D-II claw of dromaeosaurids was functionally analogous to the enlarged talon also found on D-II of extant Accipitridae (hawks and eagles; one family of the birds commonly known as “raptors”). Here, the talon is used to maintain grip on prey of subequal body size to the predator, while the victim is pinned down by the body weight of the raptor and dismembered by the beak. The foot of Deinonychus exhibits morphology consistent with a grasping function, supportive of the prey immobilisation behavior model. Opposite morphological trends within Deinonychosauria (Dromaeosauridae + Troodontidae) are indicative of ecological separation. Placed in context of avian evolution, the grasping foot of Deinonychus and other terrestrial predatory paravians is hypothesized to have been an exaptation for the grasping foot of arboreal perching birds. Here we also describe “stability flapping”, a novel behaviour executed for positioning and stability during the initial stages of prey immobilisation, which may have been pivotal to the evolution of the flapping stroke. These findings overhaul our perception of predatory dinosaurs and highlight the role of exaptation in the evolution of novel structures and behaviours

Safety, immunogenicity, and reactogenicity of BNT162b2 and mRNA-1273 COVID-19 vaccines given as fourth-dose boosters following two doses of ChAdOx1 nCoV-19 or BNT162b2 and a third dose of BNT162b2 (COV-BOOST): a multicentre, blinded, phase 2, randomised trial

Background Some high-income countries have deployed fourth doses of COVID-19 vaccines, but the clinical need, effectiveness, timing, and dose of a fourth dose remain uncertain. We aimed to investigate the safety, reactogenicity, and immunogenicity of fourth-dose boosters against COVID-19.Methods The COV-BOOST trial is a multicentre, blinded, phase 2, randomised controlled trial of seven COVID-19 vaccines given as third-dose boosters at 18 sites in the UK. This sub-study enrolled participants who had received BNT162b2 (Pfizer-BioNTech) as their third dose in COV-BOOST and randomly assigned them (1:1) to receive a fourth dose of either BNT162b2 (30 µg in 0·30 mL; full dose) or mRNA-1273 (Moderna; 50 µg in 0·25 mL; half dose) via intramuscular injection into the upper arm. The computer-generated randomisation list was created by the study statisticians with random block sizes of two or four. Participants and all study staff not delivering the vaccines were masked to treatment allocation. The coprimary outcomes were safety and reactogenicity, and immunogenicity (antispike protein IgG titres by ELISA and cellular immune response by ELISpot). We compared immunogenicity at 28 days after the third dose versus 14 days after the fourth dose and at day 0 versus day 14 relative to the fourth dose. Safety and reactogenicity were assessed in the per-protocol population, which comprised all participants who received a fourth-dose booster regardless of their SARS-CoV-2 serostatus. Immunogenicity was primarily analysed in a modified intention-to-treat population comprising seronegative participants who had received a fourth-dose booster and had available endpoint data. This trial is registered with ISRCTN, 73765130, and is ongoing.Findings Between Jan 11 and Jan 25, 2022, 166 participants were screened, randomly assigned, and received either full-dose BNT162b2 (n=83) or half-dose mRNA-1273 (n=83) as a fourth dose. The median age of these participants was 70·1 years (IQR 51·6–77·5) and 86 (52%) of 166 participants were female and 80 (48%) were male. The median interval between the third and fourth doses was 208·5 days (IQR 203·3–214·8). Pain was the most common local solicited adverse event and fatigue was the most common systemic solicited adverse event after BNT162b2 or mRNA-1273 booster doses. None of three serious adverse events reported after a fourth dose with BNT162b2 were related to the study vaccine. In the BNT162b2 group, geometric mean anti-spike protein IgG concentration at day 28 after the third dose was 23 325 ELISA laboratory units (ELU)/mL (95% CI 20 030–27 162), which increased to 37 460 ELU/mL (31 996–43 857) at day 14 after the fourth dose, representing a significant fold change (geometric mean 1·59, 95% CI 1·41–1·78). There was a significant increase in geometric mean anti-spike protein IgG concentration from 28 days after the third dose (25 317 ELU/mL, 95% CI 20 996–30 528) to 14 days after a fourth dose of mRNA-1273 (54 936 ELU/mL, 46 826–64 452), with a geometric mean fold change of 2·19 (1·90–2·52). The fold changes in anti-spike protein IgG titres from before (day 0) to after (day 14) the fourth dose were 12·19 (95% CI 10·37–14·32) and 15·90 (12·92–19·58) in the BNT162b2 and mRNA-1273 groups, respectively. T-cell responses were also boosted after the fourth dose (eg, the fold changes for the wild-type variant from before to after the fourth dose were 7·32 [95% CI 3·24–16·54] in the BNT162b2 group and 6·22 [3·90–9·92] in the mRNA-1273 group).Interpretation Fourth-dose COVID-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose

R code for Maiasaura growth curves

A modified version of the R script from Cooper et al. 2008 used to construct Maiasaura growth curves

A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana

<div><p>Background</p><p>Brachylophosaurini is a clade of hadrosaurine dinosaurs currently known from the Campanian (Late Cretaceous) of North America. Its members include: <i>Acristavus gagslarsoni</i>, which lacks a nasal crest; <i>Brachylophosaurus canadensis</i>, which possesses a flat paddle-shaped nasal crest projecting posteriorly over the dorsal skull roof; and <i>Maiasaura peeblesorum</i>, which possesses a dorsally-projecting nasofrontal crest. <i>Acristavus</i>, from the lower Two Medicine Formation of Montana (~81–80 Ma), is hypothesized to be the ancestral member of the clade. <i>Brachylophosaurus</i> specimens are from the middle Oldman Formation of Alberta and equivalent beds in the Judith River Formation of Montana; the upper Oldman Formation is dated 77.8 Ma.</p><p>Methodology/Principal Findings</p><p>A new brachylophosaurin hadrosaur, <i>Probrachylophosaurus bergei</i> (gen. et sp. nov.) is described and phylogenetically analyzed based on the skull and postcranium of a large individual from the Judith River Formation of northcentral Montana (79.8–79.5 Ma); the horizon is equivalent to the lower Oldman Formation of Alberta. Cranial morphology of <i>Probrachylophosaurus</i>, most notably the nasal crest, is intermediate between <i>Acristavus</i> and <i>Brachylophosaurus</i>. In <i>Brachylophosaurus</i>, the nasal crest lengthens and flattens ontogenetically, covering the supratemporal fenestrae in large adults. The smaller nasal crest of <i>Probrachylophosaurus</i> is strongly triangular in cross section and only minimally overhangs the supratemporal fenestrae, similar to an ontogenetically earlier stage of <i>Brachylophosaurus</i>. Sutural fusion and tibial osteohistology reveal that the holotype of <i>Probrachylophosaurus</i> was relatively more mature than a similarly large <i>Brachylophosaurus</i> specimen; thus, <i>Probrachylophosaurus</i> is not simply an immature <i>Brachylophosaurus</i>.</p><p>Conclusions/Significance</p><p>The small triangular posteriorly oriented nasal crest of <i>Probrachylophosaurus</i> is proposed to represent a transitional nasal morphology between that of a non-crested ancestor such as <i>Acristavus</i> and the large flat posteriorly oriented nasal crest of adult <i>Brachylophosaurus</i>. Because <i>Probrachylophosaurus</i> is stratigraphically and morphologically intermediate between these taxa, <i>Probrachylophosaurus</i> is hypothesized to be an intermediate member of the <i>Acristavus</i>-<i>Brachylophosaurus</i> evolutionary lineage.</p></div

<i>Probrachylophosaurus bergei</i> gen. et sp. nov. mandible.

<p>MOR 2919 (A) predentary, ventral view; (B) right dentary, lateral view; (C) right dentary, medial view; (D) right surangular, lateral view; (E) right surangular, medial view; (F) left dentary, lateral view; (G) left dentary, medial view. The anterior portion of the right dentary was crushed mediolaterally, flattening the symphyseal region into a vertical orientation. The coronoid process of the left dentary was fractured, displacing the coronoid process anteromedially. <i>Abbreviations</i>: <i>cp</i>, coronoid process; <i>path</i>, pathology; pes, proximal edentulous slope.</p

Ontogenetic and anagenetic hypothesis of brachylophosaurin evolution.

<p><i>Probrachylophosaurus bergei</i> gen. et sp. nov. is proposed as an intermediate member of the lineage leading from <i>Acristavus gagslarsoni</i> to <i>Brachylophosaurus canadensis</i>. Shaded blue areas indicate known elements of <i>Probrachylophosaurus</i>. Skull outlines of <i>Acristavus</i> and <i>Brachylophosaurus</i> are used courtesy of Terry A. Gates. The reconstruction of the MOR 1071 <i>Brachylophosaurus</i> skull is a composite of an articulated skull roof with a scaled-down copy of the MOR 794 skull outline. All skulls are scaled to the same 10 cm scale bar. The horizontal axis is not to scale; the MOR 1071 reconstruction is much closer to MOR 794 in size and hypothesized maturity than MOR 1097 is to MOR 2919. Radiometric ages have been recalibrated to the Fish Canyon sanidine standard (28.305 +/- 0.036 Ma) of Renne et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.ref010" target="_blank">10</a>] from the originally published values [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.ref003" target="_blank">3</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.ref011" target="_blank">11</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.ref013" target="_blank">13</a>]; see text and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.t001" target="_blank">Table 1</a> for further recalibration details. The age of the <i>Acristavus</i> holotype was precisely estimated by Gates et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141304#pone.0141304.ref003" target="_blank">3</a>]. The age of the Comrey Sandstone Zone of the Oldman Formation is not tightly constrained, leading to uncertainty in the exact age of <i>Brachylophosaurus</i>.</p

<i>Probrachylophosaurus bergei</i> gen. et sp. nov. skull reconstruction.

<p>(A) Preserved skull elements of MOR 2919, left lateral view. Predentary not included due to its poor preservation and diagenetic compression. (B) Outline of skull reconstruction, left lateral view. The outline accounts for diagenetic distortion of the posterior braincase, but otherwise does not correct for distortion of skull elements. Outlined regions where left skull material was not preserved are based on right bones when available. Regions with neither left nor right material preserved are hypothesized reconstructions based on <i>Brachylophosaurus canadensis</i> skulls. (C) Braincase with left nasal crest, dorsal view. (D) Outline of braincase reconstruction with nasal crest, dorsal view. Reconstruction accounts for diagenetic lateral compression and distortion of posterior braincase. <i>Abbreviations</i>: <i>d</i>, dentary; <i>ex</i>, exoccipital; <i>f</i>, frontal; <i>j</i>, jugal; <i>l</i>, lacrimal; <i>m</i>, maxilla; <i>n</i>, nasal; <i>p</i>, parietal; <i>pd</i>, predentary; <i>pf</i>, prefrontal; <i>pm</i>, premaxilla; <i>po</i>, postorbital; <i>q</i>, quadrate; <i>qj</i>, quadratojugal; <i>sa</i>, surangular; <i>sq</i>, squamosal.</p

Brachylophosaurin jugals.

<p>(A, B), <i>Probrachylophosaurus bergei</i> gen. et sp. nov. adult, MOR 2919, left jugal; (A) lateral view; (B) medial view. (C, D) <i>P</i>. <i>bergei</i> subadult, MOR 1097, right jugal reconstructed with dashed line; (C) medial view; (D) lateral view. (E, F) <i>Brachylophosaurus canadensis</i> adult, MOR 1071-7-16-98-248-Q, right jugal reversed. Note that the postorbital process was broken at its base and should be inclined more posteriorly; (E) lateral view; (F) medial view. <i>Abbreviations</i>: <i>cvf</i>, caudoventral flange; <i>lp</i>, lacrimal process; <i>pop</i>, postorbital process; <i>pp</i>, palatine process; <i>qjp</i>, quadratojugal process; <i>rp</i>, rostral process.</p