Highlights d Dinosaurs and early birds had similar relative brain sizes d Major shifts in brain-body integration occur in the aftermath of the K-Pg extinction d Rates of brain-body evolution are highest in non-avian dinosaurs, early-diverging birds, parrots, and crows d Corvids, like hominins, evolved larger relative brains and bodies simultaneously

The phylogenetic affinities of the extinct pseudo-toothed birds have remained controversial. Some authors noted that they resemble both pelicans and allies (Pelecaniformes) and tube-nosed birds (Procellariiformes), but assigned them to a distinct taxon, the Odontopterygiformes. In most recent studies, the pseudo-toothed birds are referred to the family Pelagornithidae inside the Pelecaniformes. Here, I perform a cladistic analysis with five taxa of the pseudo-toothed birds including two undescribed new species from the Early Tertiary of Morocco. The present hypothesis strongly supports a sister group relationship of pseudo-toothed birds (Odontopterygiformes) and waterfowls (Anseriformes). The Odontoanserae (Odontopterygiformes plus Anseriformes) are the sister group of Neoaves. The placement of the landfowls (Galliformes) as the sister taxon of all other neognathous birds does not support the consensus view that the Galloanserae (Galliformes plus Anseriformes) are monophyletic.

Extinct animal behavior has often been inferred from qualitative assessments of relative brain region size in fossil endocranial casts. For instance, flight capability in pterosaurs and early birds has been inferred from the relative size of the cerebellar flocculus, which in life protrudes from the lateral surface of the cerebellum. A primary role of the flocculus is to integrate sensory information about head rotation and translation to stabilize visual gaze via the vestibulo-occular reflex (VOR). Because gaze stabilization is a critical aspect of flight, some authors have suggested that the flocculus is enlarged in flying species. Whether this can be further extended to a floccular expansion in highly maneuverable flying species or floccular reduction in flightless species is unknown. Here, we used micro computed-tomography to reconstruct “virtual” endocranial casts of 60 extant bird species, to extract the same level of anatomical information offered by fossils. Volumes of the floccular fossa and entire brain cavity were measured and these values correlated with four indices of flying behavior. Although a weak positive relationship was found between floccular fossa size and brachial index, no significant relationship was found between floccular fossa size and any other flight mode classification. These findings could be the result of the bony endocranium inaccurately reflecting the size of the neural flocculus, but might also reflect the importance of the flocculus for all modes of locomotion in birds. We therefore conclude that the relative size of the flocculus of endocranial casts is an unreliable predictor of locomotor behavior in extinct birds, and probably also pterosaurs and non-avian dinosaurs.

We describe here new specimens of pseudotoothed birds (Odontopterygiformes) from the Upper Paleocene and Lower Eocene of the Ouled Abdoun Basin, Morocco. These Lower Paleogene fossils are among the oldest representatives of the Odontopterygiformes and include braincases, beak fragments, and long bones. Dasornis toliapica (Owen, 1873) (2-3 m wingspan) and Dasornis emuinus (Bowerbank, 1854) (3.5-4.5 m wingspan) were initially described from the Lower Eocene London Clay of Sheppey, England. The new species Dasornis abdoun (1.5-1.7 m wingspan) constitutes the smallest species of pseudotoothed bird ever discovered. We partly revise the oversplit taxonomy of the odontopterygiforms: the two species from the Paleogene of England and Morocco are regarded as congeneric, the name Dasornis having priority over the name Odontopteryx. We also synonymize Neptuniavis minor Harrison and Walker, 1977, and Macrodontopteryx oweni Harrison and Walker, 1976, with D. toliapica (Owen, 1873. Moreover, the genera Pelagornis Lartet, 1857, and Osteodontornis Howard, 1957, are regarded as pertaining to one single taxonomic entity that corresponds to the Pelagornis morphotype. In Dasornis, the morphological peculiarities of the humerus that are related to gliding flight are less pronounced than in Pelagornis. The latter taxon includes exceedingly specialized gliders that were most likely unable of sustained flapping flight and relied almost entirely on winds to provide lift. Pseudotoothed birds pertaining to the Dasornis morphotype were more generalists and could probably undertake flapping flight, even if limited. The species of Dasornis were soaring pelagic feeders that could disperse over large territories like extant albatrosses. They formed large breeding colonies near the shore of the

The presence of bone growth marks reflecting annual rhythms in the cortical bone of non-avian tetrapods is now established as a general phenomenon. In contrast, ornithurines (the theropod group including modern birds and their closest relatives) usually grow rapidly in less than a year, such that no annual rhythms are expressed in bone cortices, except scarce growth marks restricted to the outer cortical layer. So far, cyclical growth in modern birds has been restricted to the Eocene Diatryma , the extant parrot Amazona amazonica and the extinct New Zealand (NZ) moa (Dinornithidae). Here we show the presence of lines of arrested growth in the long bones of the living NZ kiwi ( Apteryx spp., Apterygidae). Kiwis take 5–6 years to reach full adult body size, which indicates a delayed maturity and a slow reproductive cycle. Protracted growth probably evolved convergently in moa and kiwi sometime since the Middle Miocene, owing to the severe climatic cooling in the southwest Pacific and the absence of mammalian predators.