évolution

Baminornis is the oldest known bird with a fused pygostyle, a skeletal feature that implies tail feathers. Its discovery pushed back current understanding of bird evolution and global distribution by 20 million years. Baminornis was about 15 cm in length, had many features in common with modern birds, including the capability for powered flight.

Calvarius is a genus of styracosternan ornithopod from the Late Cretaceous of Spain. The name alludes to its chronostratigraphic proximity to the extinction event that wiped out the non-avian dinosaurs at the end of the Cretaceous. The highly modified metatarsal that is known from shows an example of convergent evolution, as it is more similar to non-iguanodontian ornithopods than to other styracosternans. It is thought that this is due to fulfilling a niche in its island habitat, resulting in Calvarius becoming a small-bodied animal, capable of rapid locomotion.

Fujianvenator is an anchiornithid avialan from the Late Jurassic of China, whose discovery gave important insight to the evolution of birds. It had proportionately long legs, with the tibia twice the length of the femur. This suggests it may have been a strong runner, and possibly had a terrestrial or wading lifestyle. Fujianvenator was a small dinosaur, weighing about 640 g. As an avialan, it was almost certainly covered in feathers, though it does not seem likely to have been capable of flight.

Figure 1. Evolution of macroecological traits in Dinosauria. Large scale event in dinosaur evolution (a); the origin of dinosaurs (star), hyperthermals (volcano), the earliest fossil Avialae (bird), the earliest fossil angiosperm (flower), the Cretaceous/Palaeogene mass extinction (asteroid). Phylogeny of dinosaurs (b) redrawn from Sereno and adapted to the current consensus and upon which an ancestral state reconstruction of temperature niche (mean annual temperature) after Chiarenza et al. is plotted; Mesozoic palaeogeographies (c) for Triassic (T), Jurassic (J) and Cretaceous (K). Silhouette colours symbolize body mass for each of the taxa represented; information on dietary habits are plotted after Barrett and Zanno & Makovicky; numbers represent clades discussed through this study: 1, Ornithischia; 2, Thyreophora; 3, Ornithopoda; 4, Hadrosauroidea; 5, Marginocephalia; 6, Ceratopsia; 7, Saurischia; 8, Sauropodomorpha; 9, Sauropoda; 10, Theropoda; 11, Ceratosauria; 12, Tetanurae; 13, Coelurosauria; 14, Maniraptoriformes; 15, Maniraptora; 16, Deinonychosauria; 17, Avialae; 18, Ornithothoraces. Palaeogeographies modified from original plots via R package ‘mapast’ using plate models by Scotese.

Reconstruction of three Elasmosaurus hunting Hesperornis. From Osborn, H. F. (1917). The origin and evolution of life, on the theory of action, reaction and interaction of energy.

Body mass evolution of Oviraptorosauria. Time calibrated phenograms of Log10 Body Mass (kg) versus time (Ma) for Oviraptorosauria. Blue halos represent 95% confi- dence intervals and branches indicate phylogenetic relation- ships. Each plot displays the same data, but Caenagnathidae is highlighted in green in (A) and Oviraptoridae is highlighted in red in (B) for clarity. Yellow arrows indicate nodes where important changes in body size range occur. Pie charts show ancestral estimations of biogeographic range (as in Fig. 20) for important clades of caenagnathids (A) and oviraptorids (B). Node labels from left to right in (A): Oviraptorosauria; Caenagnathidae; Anomalipes + Caenagnathinae; Caenagnathinae more derived than Apatoraptor pennatus; Anzu + Caenagnathus. Node labels from left to right in (B): Oviraptorosauria; Caenagnathoidea; Oviraptoridae; Heyuanninae (bottom); Citipatinae (top). Colours for node labels as in Fig. 20. Abbreviations: Al, Albian; Ap, Aptian; Ba, Barremian; Be, Berriasian; Ca, Campanian; Ce, Cenomanian; Co, Coniacian; Ha, Hauterivian; Ma, Maastrichtian; S, Santonian; Tu, Turonian; Va, Valanginian.

Reconstructed skull of Wiehenvenator albati based on holotype specimen (white). Scale bar is 10cm, image if 10px/cm. Unknown material based on related Torvosaurus tanneri. Cranial anatomy based on Rauhut et al (2016) "A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: implications for theropod evolution and faunal turnover in the Jurassic"

Menefeeceratops is a genus of ceratopsid dinosaur from the Menefee Formation in the United States. It is is believed to have been approximately 4 m long, and had two large horns above the eyes like other ceratopsians. Menefeeceratops was one of the earliest and most basal known members of the ceratopsids, and the oldest known centrosaurine. Its age and location was instrumental in helping to understand the evolution and diversification of the centrosaurine dinosaurs.

Rates of skeletal character evolution in the skull and postcranial skeleton of hadrosauroids. Cladograms illustrate the results from branch likelihood tests for two morphological partitions: skull (cranium and mandible) (A) and postcranial skeleton (B). In both cladograms, results from the branch likelihood tests are summarized on a strict consensus tree derived from four separately analyzed MPTs, each with 100 dating replicates (a total of 400 Hedman-dated phylogenies). Pie charts on branches illustrate the proportion of dating replicates that showed significantly high rates (red), slow rates (blue), or nonsignificant average rates (white). No pie charts are plotted on branches that showed nonsignificant rates in 100% of dating replicates. Branches that showed high rates (red) in more than 50% of dating replicates are doubled in length. See the Supplementary Material for Hedman-based results plotted separately for each MPT (Supplementary Fig. S2) and for results using the MBL dating method (Supplementary Fig. S3). Silhouettes were created by Scott Hartman and were downloaded from http://phylopic.org (Creative Commons license CC BY 3.0).

Phylogenetic affinities of Saltriovenator and evolution of the hand in Theropoda. Reduced strict consensus of the shortest trees found by the phylogenetic analysis after pruning of Lewisuchus and Teleocrater. Numbers at nodes indicate decay index. Inferred manual phalangeal formula for selected nodes indicated below clade names. Hands of representative members of the avian stem (bold names) in extensor view (Herrerasaurus in flexor view), medial side at left, missing elements in white based on ancestral states inferred at least inclusive node containing the taxon. Red star indicates loss of metacarpal V, blue stars indicate multiple independent losses of metacarpal IV among tetanurans. Drawings by A. Cau.

Map of the Late Cretaceous (90 Ma)

This is a collage that represents three periods of Neoproterozoic and is composed of three images from Commons: File:Otavia antiqua 3D reconstruction.jpg represents Tonian period (1000-720 mya), marked by start of evolution of animals. File:AntarcticaDomeCSnow.jpg represents Cryogenian period (720-635 mya), marked by worldwide glaciations (aka "Snowball Earth"). File:Life in the Ediacaran sea.jpg represents Ediacaran period (635-541 mya), marked by first recognizable animal fauna - vendobionts.

Tylosaurus reconstruction. From Osborn, H. F. (1917). The origin and evolution of life, on the theory of action, reaction and interaction of energy.

Skull of Saichania, Warsaw Museum of Evolution