View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Crossref J Ornithol (2015) 156:837–846 DOI 10.1007/s10336-015-1164-y ORIGINAL ARTICLE A primitive heron (Aves: Ardeidae) from the Miocene of Central Asia Andrzej Elzanowski • Nikita V. Zelenkov Received: 14 October 2014 / Revised: 1 January 2015 / Accepted: 19 January 2015 / Published online: 11 February 2015 Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract A robust quadrate from the Middle Miocene of Keywords Fossil birds Á Quadrate skull Á Mongolia represents a new genus of Ardeidae that com- Neck curvature Á Miocene bines the similarities to Nycticorax and Tigrisoma, both of which have been recovered in basal positions in recent Zusammenfassung phylogenies of the Ardeidae, and to cf. Pikaihao from the Middle Miocene of Africa. The confluence of mandibular Ein primitiver Reiher (Aves: Ardeidae) aus dem Mio- facets on the medial condyle and pterygoid condyle in the za¨n Zentralasiens new genus, Nycticorax, and cf. Pikaihao is likely to be symplesiomorphic, as it is shared with nearly all other Aufgrund eines robusten Quadratums aus dem Mittel- waterbirds (except for the Ciconiidae), including the im- Mioza¨n der Mongolei wird eine neue Art und Gattung der mediate outgroup (Threskiornithidae). However, the me- Ardeidae erstellt. Das Quadratum verbindet die Merkmale dial supraorbital crest is a likely synapomorphy of the new von Tigerreihern (Tigrisoma) und Nachtreihern (besonders genus and cf. Pikaihao. The similarities to Trigrisoma Nycticorax), die wiederholt in basalen Stellungen in support its basal position, as recovered from molecular Stammba¨umen der Ardeidae resultierten, als auch von cf. sequences and proposed by a pre-cladistic morphological Pikaihao aus dem Mittel-Mioza¨n Afrikas. Das Ver- analysis. Since both the night herons and Tigrisoma have schmelzen der Mandibularfazetten auf dem condylus heads that are proportionally much larger than those of the mandibularis medialis und condylus pterygoideus, wie large day herons, it appears that the Ardeidae started their auch bei Nycticorax und cf. Pikaihao, weist auf einen evolution with relatively heavy heads, which may have primitiven Vertreter der Ardeidae hin weil es dem ganzen contributed to the origins of the family-specific head re- Stamm der Wasservo¨gel (bis auf Ciconiidae) eigen ist und traction in flight. auch bei der unmittelbaren Außengruppe (Threskiornithi- dae) vorkommt. Jedoch erscheint die crista suprorbitalis medialis als eine Synapomorphie der Nyctisoma und cf. Communicated by F. Bairlein. Pikaihao. Die Gemeisamkeiten mit Tigrisoma dagegen erweisen sich eher als symplesiomorph und besta¨tigen die Electronic supplementary material The online version of this article (doi:10.1007/s10336-015-1164-y) contains supplementary basale Stellung von Tigerreihern, die von einer pra¨-k- material, which is available to authorized users. ladistischen Analyse und einer Molekularphylogenie nicht aber von den rezenten kladistischen, aufgrund der mor- & A. Elzanowski ( ) phologischen Merkmalen berechneten Stammba¨umen Museum and Institute of Zoology, Polish Academy of Sciences, 64 Wilcza Street, 00-679 Warsaw, Poland festgestellt wurde. Sowohl bei den Tigerreihern als auch e-mail: [email protected] bei den Nachtreihern sind die Ko¨pfe relativ gro¨ßer als bei den großen Tagreihern, was darauf hindeutet, dass der N. V. Zelenkov Kopf auch bei den ancestralen Ardeidae relativ schwer war Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow 117997, Russia und damit zur Entstehung der S-fo¨rmigen Halsbeugung im e-mail: [email protected] Fluge beitragen konnte. 123 838 J Ornithol (2015) 156:837–846 Introduction herons.’’ The latter observation is mistaken; in fact, the position of the caudomedial foramen, shared with the re- The family Ardeidae (herons, night herons and bitterns) lated Threskiornithidae, is remarkably stable among the comprises 62 extant species in 17 genera (Kushlan and Ardeidae, although the foramen varies in shape. Measure- Hancock 2005). The ardeid lineage must have split from its ments from numerous specimens of Nycticorax nycticorax sister group, the Threskiornithidae (Hackett et al. 2008)by and Nyctanassa violacea have demonstrated moderate the Middle Eocene, when the oldest ibis has been identified sexual dimorphism in the size of quadrates (Adams 1955), (Mayr 2009). However, no stem-group ardeid has ever and permit calculating their intraspecies and intrasex been identified and no Eocene predecessors of herons have variability as 109–115 % of the smallest specimen, which yet been found, except for the inherently questionable should be taken into account by avian paleontologists who tracks (Mustoe 1993). The oldest unquestionable ardeid often establish new species based on size differences. In fossils come from the early Oligocene (Mayr 2009), in- addition, Bas (1954) illustrated the quadrate in Ardea cluding remnants of two unnamed species from the Jebel cinerea to show the origin area of the protractor ptery- Qatrani formation of Egypt, one of them being a tar- goidei et quadrati. sometatarsus that is indistinguishable from that of extant Here, we describe a quadrate belonging to a new species night herons Nycticorax (Rasmussen et al. 1987). Proardea and genus of a primitive heron from the Middle Miocene amissa has been recorded form the late Oligocene of Sharga locality in Mongolia, which is one of the richest Quercy (Mayr 2009). In the early Miocene, Proardeola localities of Neogene birds of Asia (Zelenkov and walkeri was widespread across Europe and Asia (Zelenkov Kurochkin 2011). This locality yielded numerous avian 2011 and references therein), and two approximately co- fossils (see Zelenkov 2013 for review), including a new eval species, an unusual ardeid Matuku otagoenese and a species, Ardea sytchevskayae, and two unnamed species putative botaurine Pikaihao bartlei, have been described based on very fragmentary material: one, larger, referred to from New Zealand (Scofield et al. 2010; Worthy et al. Botaurinae and another, smaller, that could not be referred 2013). A coracoid of a large ardeid, possibly a Cochlearius to any taxon (Zelenkov 2011). relative, has been described as Zeltornis ginsburgi from the lower Miocene of northern Africa (Balouet 1981). In the middle Miocene, the extant genus Ardea appears to be of Materials and methods North America (Becker 1986) and Asia, where two other unnamed species, one of them assigned to the Botaurinae, The quadrate is lacking most of the orbital process and have also been found (Zelenkov 2011). An ardeid identified approximately the distal half of the pterygoid condyle (the as cf. Pikaihao was reported from the middle Miocene of entire pterygoid facet and the distal part of the secondary Africa (Mayr 2014). A morphologically unique tar- mandibular facet are cut off). Otherwise, the bone is well sometatarsus of a large ardeid (the size of Ardea goliath) preserved. The anatomical terminology (formal Latin in has been described as Ardeagrandis arborea from the late Fig. 1 and anglicized in the text) follows Elzanowski et al. middle to early late Miocene of Moldova (Kurochkin and (2000) with a few additions. Ganya 1972). The late Miocene record of Ardeidae consists For comparisons we surveyed 24 extant species in 14 primarily of the extant genera (Ardea, Ardeola, Botaurus, genera of Ardeidae: Agamia agami, Ardea alba, A. cinerea, Egretta, Nyctanassa, Nycticorax). A. goliath, A. herodias, A. melanocephala, A. purpurea, The quadrate is one of the most frequently preserved, Ardeola ralloides, Botaurus stellaris, Butorides striata, single cranial bones in the avian fossil record, and yet up Bubulcus ibis, Cochlearius cochlearius, Egretta caerulea, until recently, it has been given little attention by avian E. garzetta, E. thula, Gorsachius melanolophus, Ixo- paleontologists, certainly due to the lack of any detailed brychus eurhythmus, I. minutus, Nyctanassa violacea, comparative study of this bone in extant birds. The situa- Nycticorax caledonicus, N. nycticorax, Syrigma sibilatrix, tion has greatly improved only recently, allowing Scofield Tigrisoma lineatum and T. mexicanum. In addition, we et al. (2010) to provide a detailed description of the unusual included into comparisons the quadrates of two fossil ardeid quadrate (with an enormous tympanic crest) of species: Matuku otagoense, as described by Scofield et al. Matuku otagoense, and Mayr (2014) illustrated the quad- (2010), and cf. Pikaihao, using the original photographs for rate of cf. Pikaihao. For extant species, Payne and Risley Mayr (2014; Fig. 2a–e). (1976) compared some cranial details in most ardeid spe- We used Threskiornithidae as an immediate outgroup, cies, but paid little attention to the quadrate, except for following Hackett et al. (2008). Although the quadrates of finding it strikingly different in Cochlearius (which is the threskiornithids and ardeids are dissimilar in most de- correct) and noting a variation in the position of ‘‘a small tails, they share the caudomedial foramen, which is there- pneumatic foramen,’’ ‘‘particularly among the night fore a likely synapomorphy of these two families, whereas 123 J Ornithol (2015) 156:837–846 839 Fig. 1 Left quadrates of Ardeidae. a Nycticorax nycticorax, b Nyctisoma robusta holotype PIN 4869/52 from the middle Miocene of Sharga locality (Western Mongolia), c Tigrisoma mexicanum, d Nyctanassa violacea, e Botaurus