royalsocietypublishing.org/journal/rspb Research Cite this article: van Heteren AH et al. 2021 New Zealand’s extinct giant raptor (Hieraaetus moorei) killed like an eagle, ate like a condor. Proc. R. Soc. B 288: 20211913. https://doi.org/10.1098/rspb.2021.1913 Received: 30 August 2021 Accepted: 10 November 2021 Subject Category: Morphology and biomechanics Subject Areas: biomechanics, evolution, palaeontology Keywords: diet, Haast’s eagle, Hieraaetus, finite-element analysis, geometric morphometrics Authors for correspondence: A. H. van Heteren e-mail: vanheteren@snsb.de S. Wroe e-mail: swroe@une.edu.au Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare. c.5715240. New Zealand’s extinct giant raptor (Hieraaetus moorei) killed like an eagle, ate like a condor A. H. van Heteren 1,2,3,4 , S. Wroe 4 , L. R. Tsang 4,5 , D. R. Mitchell 4,6 , P. Ross 7 , J. A. Ledogar 8 , M. R. G. Attard 4,9,10 , D. Sustaita 11 , P. Clausen 7 , R. P. Scofield 12 and G. Sansalone 4 1 Sektion Mammalogie, Zoologische Staatssammlung München - Staatliche Naturwissenschaftliche Sammlungen Bayerns, Münchhausenstraße 21, 81247 Munich, Germany 2 GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Straße 10, 80333 Munich, Germany 3 Department Biologie II, Ludwig-Maximilians-Universität München, Großhaderner Straße 2, 82152 Planegg- Martinsried, Germany 4 School of Environmental and Rural Science, University of New England, Earth Sciences Building, NSW 2351 Armidale, Australia 5 Ornithology Collection, Australian Museum Research Institute, 1 William Street, Sydney, Australia 6 College of Science and Engineering, Flinders University, SA 5042 Adelaide, Australia 7 School of Engineering, University of Newcastle, NSW 2308 Newcastle, Australia 8 Department of Evolutionary Anthropology, Duke University, Durham, NC 27798, USA 9 School of Engineering and Innovation, Open University: Milton Keynes, Buckinghamshire, UK 10 Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK 11 Department of Biological Sciences, California State University San Marcos, 333 S. Twin Oaks Valley Rd., San Marcos, CA 92096, USA 12 Natural History, Canterbury Museum, Rolleston Avenue, 8013 Christchurch, New Zealand AHvH, 0000-0003-1018-7991; SW, 0000-0002-6365-5915; DRM, 0000-0003-1495-4879; MRGA, 0000-0002-8509-3677; DS, 0000-0001-9932-909X; RPS, 0000-0002-7510-6980 The extinct Haast’s eagle or harpagornis (Hieraaetus moorei) is the largest known eagle. Historically, it was first considered a predator, then a scaven- ger, but most recent authors have favoured an active hunting ecology. However, the veracity of proposed similarities to carrion feeders has not been thoroughly tested. To infer feeding capability and behaviour in har- pagornis, we used geometric morphometric and finite-element analyses to assess the shape and biomechanical strength of its neurocranium, beak and talons in comparison to five extant scavenging and predatory birds. The neurocranium of harpagornis is vulture-like in shape whereas its beak is eagle-like. The mechanical performance of harpagornis is closer to extant eagles under biting loads but is closest to the Andean condor (Vultur gryphus) under extrinsic loads simulating prey capture and killing. The talons, however, are eagle-like and even for a bird of its size, able to withstand extremely high loads. Results are consistent with the proposition that, unlike living eagles, harpagornis habitually killed prey larger than itself, then applied feeding methods typical of vultures to feed on the large carcasses. Decoupling of the relationship between neurocranium and beak shape may have been linked to rapid evolution. 1. Introduction Accipitrid birds of prey (Aves: Accipitriformes) are a diverse group composed of eagles, kites and Old World vultures. Raptorial birds predominately feed on animals and have specific prey preferences. Some raptorial species specialize on mammals, reptiles, amphibians, fish, other birds or carrion, whereas others are generalists, feeding on a variety of prey, including invertebrates [1]. Different feeding preferences among raptorial birds require different hunting strategies and consequently divergently adapted morphological structures [1–3]. For © 2021 The Author(s) Published by the Royal Society. All rights reserved. Downloaded from https://royalsocietypublishing.org/ on 03 December 2021