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Large euenantiornithine birds from the Cretaceous of southern France, North America and Argentina

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We review historical approaches to the systematics of Enantiornithes, the dominant birds of the second half of the Mesozoic, and describe the forelimb remains of a new Cretaceous euenantiornithine. This taxon is known on the basis of fossil specimens collected from southern France, Argentina and the United States; such a wide geographical distribution is uncharacteristic for Enantiornithes as most taxa are known from single localities. Fossils from the Massecaps locality close to the village of Cruzy (Hérault, southern France), in combination with elements from New Mexico (USA) and from the Argentine locality of El Brete (Salta Province) testify to the global distribution of large flighted euenantiornithine birds in the Late Cretaceous. We discuss the systematics and taxonomy of additional isolated bones of Enantiornithes that were collected from the Argentine El Brete locality in the 1970s; the presence of these flying birds in Cretaceous rocks on both sides of the equator, in both northern and southern hemispheres, further demonstrates the ubiquity of this avian lineage by the latter stages of the Mesozoic.
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Geol. Mag. 144 (6), 2007, pp. 977–986. c
2007 Cambridge University Press 977
doi:10.1017/S0016756807003871 First published online 26 September 2007 Printed in the United Kingdom
Large euenantiornithine birds from the Cretaceous of southern
France, North America and Argentina
C. A. WALKER, E. BUFFETAUT&G.J.DYKE
Department of Palaeontology, The Natural History Museum London, Cromwell Road, SW7 5BD, London, UK
CNRS, UMR 5125, (Pal´
eoenvironnements et Pal´
eobiosph`
ere), 16 cour du Li´
egat, 75013 Paris, France
School of Biology and Environmental Science, University College Dublin, Belfield Dublin 4, Ireland
(Received 29 December 2006; accepted 15 February 2007)
Abstract – We review historical approaches to the systematics of Enantiornithes, the dominant
birds of the second half of the Mesozoic, and describe the forelimb remains of a new Cretaceous
euenantiornithine. This taxon is known on the basis of fossil specimens collected from southern
France, Argentina and the United States; such a wide geographical distribution is uncharacteristic for
Enantiornithes as most taxa are known from single localities. Fossils from the Massecaps locality close
to the village of Cruzy (H´
erault, southern France), in combination with elements from New Mexico
(USA) and from the Argentine locality of El Brete (Salta Province) testify to the global distribution of
large flighted euenantiornithine birds in the Late Cretaceous. We discuss the systematics and taxonomy
of additional isolated bones of Enantiornithes that were collected from the Argentine El Brete locality
in the 1970s; the presence of these flying birds in Cretaceous rocks on both sides of the equator, in
both northern and southern hemispheres, further demonstrates the ubiquity of this avian lineage by the
latter stages of the Mesozoic.
Keywords: palaeontology, anatomy, Mesozoic, France, Argentina, New Mexico, flight.
1. Introduction
Over the last two decades the number of fossil birds
known from the Cretaceous has ballooned; more fossils
have been discovered and described since the early
1980s than were known for almost the entire preceding
century (Chiappe, 1995; Kurochkin, 1995; Chiappe &
Dyke, 2002; Fountaine et al. 2005) (Fig. 1). Because of
this explosion in the known record, several new lineages
of fossil birds have been discovered and documented,
among them Enantiornithes (Walker, 1981; Kurochkin,
2001; Chiappe & Walker, 2002). This clade is now
thought to have been the most diverse group of
flying birds throughout the Cretaceous, comparable
in morphological and taxonomic diversity to that of
modern birds (Chiappe & Walker, 2002). The flight
styles of these birds mirrored those seen amongst their
modern counterparts (Neornithes) (Rayner & Dyke,
2002) and some were even flightless (Chiappe et al.
2006).
Our current understanding of the evolution of
enantiornithine birds dates from the work of Walker
(1981), who recognized novel morphologies in a
collection of Late Cretaceous bones which had been
shown to him by J. Bonaparte in the 1970s (Bonaparte
was then working at the Universidad de Tucuman,
Argentina). Bonaparte had collected a series of fossil
bones between 1974 and 1976 (with help from J. Leal)
Author for correspondence: gareth.dyke@ucd.ie
from continental deposits of the Maastrichtian Lecho
Formation in Salta Province, northwestern Argentina
(Bonaparte et al. 1977; Bonaparte & Powell, 1980)
(Fig. 2). Bonaparte took this collection of largely
isolated bones to the USA where he showed them to
the late Pierce Brodkorb; because Brodkorb told him
that these elements ‘did not belong to birds’, he carried
them on to London where they were examined in The
Natural History Museum by Walker. A description
and short analysis of some of the original El Brete
collection followed (Walker, 1981); however, the bulk
of this collection still remains undescribed, even though
it has formed the basis for much subsequent descriptive
and phylogenetic work on Enantiornithes (e.g. Brett-
Surman & Paul, 1985; Chiappe, 1993, 1996; Chiappe &
Walker, 2002). Walker (1981) based his diagnosis for
‘Enantiornithes’ on the anatomy of the forelimb and
shoulder girdle; limited subsequent taxonomic work on
the El Brete collection (Chiappe, 1993, 1996) focused
instead on the hindlimb, in particular the anatomy of
the tarsometatarsus.
In this paper we review previous taxonomic studies
and note that Walker’s original manuscript, later to form
the basis for his 1981 publication, was much longer
than in its final published form (Chiappe & Walker,
2002; cited in Chiappe, 1991, as ‘in preparation’). We
also provide a historical review of early ideas about
enantiornithine taxonomy (1980s) and describe a new
taxon that was originally identified (but never fully
documented) by Walker in the 1980s. Some elements of
978 C. A. WALKER, E. BUFFETAUT & G. J. DYKE
Figure 1. Collector curves to show increasing numbers of known
Mesozoic birds since the 1980s: (a) increasing proportion of all
known specimens, and (b) distribution of geological ages. From
Fountaine et al. (2005).
Figure 2. Maps showing the locations of El Brete (Argentina)
and Massecaps (France). Regions of countries are shown as
shaded boxes, localities as filled dots.
this new bird were figured by Walker (1981). Based on
well-preserved humeri, this new Late Cretaceous bird
is well represented in the original El Brete collections,
and has more recently been discovered in sediments
of the same age in southern France. Also collected
in the mid-1970s, one additional bone also testifies to
the presence of this taxon in the North American Late
Cretaceous.
2. Material and methods
Repositories for specimens, and abbreviations used
in the text, are indicated by the following acronyms:
BMNH – The Natural History Museum, London, UK
(Palaeontology Department collections); KU-NM –
University of Kansas, Museum of Natural History,
Lawrence, Kansas, USA; ACAP – Mus´
ee de Cruzy,
Cruzy (l’Association Culturelle, Arch´
eologique et
Pal´
eontologique de l’Ouest Biterrois), Cruzy, France;
PVL – Fundaci´
on-Instituto Miguel Lillo, Tucum´
an,
Argentina. Although our illustrations are of original
specimens (PVL), some of our anatomical descriptions
are based on casts made in London in the 1980s
(BMNH).
3. Historical review
In the late 1970s, pre-cladistic views of avian phylogeny
and classification recognized three ‘subclasses’ of
birds, termed ‘Archaeornithes’, ‘Odontornithes’ and
‘Neornithes’. Examination of the morphology of the El
Brete specimens, brought to London by J. Bonaparte,
led Walker to name a new avian group, which he
termed the subclass ‘Enantiornithes’ (Walker, 1981) to
accommodate these (at the time) strange forms. Once
published, not everyone agreed with this interpretation:
at the time, considerable doubt was expressed verbally
and in print concerning the ‘avian affinities’ of Enanti-
ornithes (Steadman, 1983). Later, and as more material
came to light, Walker’s (1981) identification became
more generally accepted in the literature (Elzanowski,
1981; Martin, 1983; Thulborn, 1984; Kurochkin, 1985;
Olson, 1985; Cracraft, 1986; see review in Chiappe &
Walker, 2002). Some authorities, however, remained
unconvinced and still considered that at least part,
if not all, of Walker’s ‘enantiornithine assemblage’
was ‘reptilian’ (Steadman, 1983; Brett-Surman &
Paul, 1985). The turning point came with subsequent
reinterpretation of Alexornis antecedens, a sparrow-
sized bird from the Cretaceous of Mexico that had
been originally described as a ‘coraciiform/piciform
ancestor’ by Brodkorb (1976). Walker (1981) noted
similarities between the humerus of this taxon and
elements from El Brete (which we discuss in this
paper); critics of the ‘enantiornithine’ hypothesis had
up until then not questioned the avian affinity of
Alexornis, anatomically comprising little more than a
scaled-down version of some of the bones from El Brete
Euenantiornithine birds 979
(Walker, 1981). This connection was communicated to
L. D. Martin by Walker, and eventually appeared in
Martin (1983); Brodkorb (1976) had understandably
mis-identified the scapula and coracoid of Alexornis.
Martin (1983), in the same paper, also suggested
placing the ‘ratite-like’ Gobipteryx (Elzanowski, 1974,
1977), from the Cretaceous of Mongolia, within
Enantiornithes. Martin (1983) referred specifically
to the morphology of an undescribed lower jaw
from Argentina, figured by Elzanowski (1977); this
suggestion, like Martin’s (1983) comment on Alexornis,
was also criticized by Steadman (1983). Nevertheless,
description of additional, incomplete, specimens of
anatomically similar fossil birds followed in the 1980s;
further isolated bones from the Cretaceous were next
described and figured by Nessov (1984). Two small
genera were recognized: Zhyraornis kashkarovi, which
was thought closely related to the marine Ichthyornis;
and Kizylkumavis cretacea, which Nessov (1984)
likened to the similarly sized Alexornis (and thus to
Enantiornithes). The distal part of a humerus that is the
type and only known specimen of Kizylkumavis was
considered enantiornithine by Walker in his original
manuscript; it has a dorsoventrally curved distal end
with poorly developed condyles on its cranial surface
(Chiappe & Walker, 2002).
In general, a dearth of fossil birds, let alone speci-
mens well-enough preserved to corroborate Walker’s
(1981) ‘Enantiornithes’, formed the research materials
of the 1980s (Fig. 1) (Harrison & Walker, 1973;
Brodkorb, 1978; Feduccia, 1980; Martin, 1983; Olson,
1985; see Feduccia, 2006). It is in this context
that the approaches and methodologies used, as well
as the conclusions reached, by early students of
Enantiornithes must be viewed.
Walker (1981) hypothesized that: (1) Enantiornithes
would prove to be widespread, that they likely enjoyed
a global distribution in the Cretaceous; and that (2)
Enantiornithes would prove to be the most abundant
group of Mesozoic birds, but that their range would be
restricted to the Cretaceous. Both of Walker’s (1981)
hypotheses have been borne out by subsequent fossil
discoveries (Fig. 3) (Kurochkin, 1995, 1996; Feduccia,
1999, 2006; Zhang & Zhou, 2000; Zhang et al. 2000;
Chiappe & Walker, 2002; Fountaine et al. 2005).
4. Geological setting and fossil associations
4.a. Southern France
The French specimen described here was collected
during the course of systematic excavations at the
Massecaps locality close to the village of Cruzy,
H´
erault, southern France (Fig. 2). Excavations in
this area are conducted by the Centre National de
la Recherche Scientifique (CNRS) and the Associ-
ation Culturelle, Arch´
eologique et Pal´
eontologique de
l’Ouest Biterrois (ACAP); this Massecaps locality
Figure 3. Map to show the known geographic distribution and
relative ages of Enantiornithes alongside the other main lineages
of Mesozoic birds (re-drawn from Chiappe & Dyke, 2002).
has yielded an abundant and diverse fauna of Late
Cretaceous vertebrates, mostly represented by isolated
elements, including lepisosteid fish, coelacanths, am-
phibians, turtles, varanoid lizards, mammals, dinosaurs
and enantiornithine birds (Buffetaut, 1998, 2005;
Buffetaut et al. 1999; Cavin et al. 2005). Remains
of enantiornithines, consisting of a coracoid and a
fragmentary femur, were first reported from Massecaps
by Buffetaut (1998).
This region of France, a hilly area located between
the coastal plain that borders the Mediterranean and
the Palaeozoic massif of the Montagne Noire (Fig. 2),
is the expression of a complex geological structure that
was folded and faulted during the Cenozoic. In this
area the Late Cretaceous is well represented by fluvial
red beds that comprise conglomerates, sandstones and
clays, and are overlain by freshwater limestones; these
deposits are often referred to as the ‘Gr`
es `
a reptiles’
(Buffetaut, 2005). Although precise dating of these
sediments has proved difficult (Buffetaut, 2005), the
vertebrate assemblage, especially from the Cruzy area,
is consistent with a late Campanian–early Maastrich-
tian age. This has been corroborated by the presence of
certain types of dinosaur eggs which suggest an early
Maastrichtian age (Garcia & Valentin, 2001–2002).
4.b. Argentina
All the Argentine specimens were collected as mainly
isolated elements from a small quarry (J. Bonaparte,
pers. comm.) about 8 m wide, roughly in the mid-
section of the Lecho Formation in Salta Province
980 C. A. WALKER, E. BUFFETAUT & G. J. DYKE
(Walker, 1981). As reported in Chiappe (1991, 1993),
the Lecho Formation is part of the Late Cretaceous
Salta Group of sediments, part of the much larger
Andean sedimentary basin (Bonaparte et al. 1977). All
the bird bones examined by Walker in the BMNH were
collected by J. Bonaparte and J. Leal from fine-grained
sandstones within the Lecho Formation (Fig. 2); for
more details relevant to the geological context of these
specimens, see Chiappe (1991). Because of the non-
associated nature of the bird bones from El Brete, direct
anatomical comparisons other than on the basis of size
cannot be corroborated. As noted by Walker (1981)
and Chiappe (1993), this ‘lack of association’ means
that fore- and hindlimb bones cannot definitively be
associated with one another.
5. Systematic palaeontology
AVES Linnaeus, 1758
ORNITHOTHORACES Chiappe, 1996
ENANTIORNITHES Walker, 1981
EUENANTIORNITHES Chiappe, 2002
Genus Martinavis nov.
Type species. Martinavis cruzyensis, described below.
Etymology. The generic name is in honour of Larry D.
Martin, in recognition of his contributions to the study
of Mesozoic birds and for his support of Cyril Walker
in the 1980s. Many of the original illustrations of the
El Brete collection were rendered by KU-NM artists in
the 1980s (Chiappe & Walker, 2002).
Diagnosis. An euenantiornithine bird that possesses
the following unambiguous synapomorphies of the
humerus (based on the phylogenetic analysis detailed
in Chiappe, 2002, and Chiappe & Walker, 2002):
dorsal margin concave in its central portion, rising both
ventrally and dorsally on either side; bicipital crest
prominent (well developed and broad); and ventral
surface of bicipital crest bearing a small fossa for
muscle attachment. In addition, this taxon shares with
other members of Enantiornithes the presence of: an
‘L-shaped’ articulation between the proximal part of
the humerus and the coracoid (seen in proximal view:
Walker, 1981); a well-marked depression underneath
the proximal head of the humerus; weakly developed
distal condyles; and a flat distal end that is not deflected
dorsally (Chiappe & Walker, 2002). Additional charac-
teristics of Martinavis include: wide pneumotricipital
fossa; unperforated ventral tuberculum; flat and broad
deltopectoral crest that joins the shaft smoothly and
lacks any degree of ventral curvature; small and boss-
like bicipital crest that is projected cranially; ventral
martin of bicipital crest small with distally located
fossa; ventral tuberculum does not bear proximodistal
canal; distal end with poorly developed ventral condyle;
ectepicondyle and entepicondyle lack marked tricipital
grooves; ventral condyle enlarged and extended distally
to below level of the dorsal and ventral condyles;
external condyle transversely orientated.
Differential diagnosis. Martinavis comprises a taxon
of euenatiornithine bird easily differentiated from the
contemporaneous Enantiornis (from the same El Brete
locality) on the basis of its more gracile humerus and
in the morphology of its deltopectoral crest (Fig. 4).
Distinct differences in comparison with other euenan-
tiornithines include the fact that the surface between
the shaft and the deltopectoral crest is smoothly angled
(Fig. 4). This bird also has a bicipital crest that is
not inclined caudally, a small entepicondyle, a laterally
positioned ectepicondyle, and a transversely orientated
external (dorsal) condyle. As we have noted above
and has been discussed elsewhere (Walker, 1981;
Chiappe, 1993), direct comparisons between bones
referred here to Martinavis and the other El Brete
euenantiornithines (apart from Enantiornis): Lectavis,
Yungavolucris and Soroavisaurus (Chiappe, 1993), all
based on tarsometatarsi, are impossible because these
elements were not collected in association. Note that
Martinavis is similar in its preserved morphology with
Gurilynia, described from the Late Cretaceous of the
Gobi Desert, Mongolia (Kurochkin, 1999); discussion
of this will follow in a later paper.
Martinavis cruzyensis sp. nov.
Holotype. ACAP-M 1957, a complete uncrushed right
humerus (Fig. 4a–d) preserved in three dimensions. In
caudal view, the deltopectoral crest of this specimen
is cracked at about its midpoint. This specimen is
one of the largest euenantiornithine forelimb bones
to be collected from the European Cretaceous and
remarkably is almost identical to Argentine specimens
from El Brete, collected some 20 years earlier (Fig. 4).
Etymology. For the village of Cruzy, H´
erault, southern
France, where this specimen was collected (Massecaps
locality) (Fig. 2).
Type locality. Late Campanian–early Maastrichtian
sediments (Massecaps locality), close to the village of
Cruzy, H´
erault, southern France (Fig. 2).
Diagnosis. Euenantiornithine bird exhibiting the fol-
lowing characters: bicipital crest of humerus strongly
projected cranially; capital groove deeply depressed
and wide; attachment site for m. pectoralis depressed
and broad; absence of well-defined proximodistal
groove on ventral tuberculum; internal (ventral) and
external (dorsal) condyles greatly enlarged and expan-
ded; ventral epicondyle enlarged and extended distally.
Martinavis vincei sp. nov.
Holotype. PVL 4054, complete left humerus (Fig. 4e).
Paratype. PVL 4059, distal end of left humerus (Fig.
4f).
Euenantiornithine birds 981
Figure 4. Humeri referred to Martinavis (see text for details): ACAP-M 1957, complete right humerus (holotype of M. cruzyensis)in
left lateral (a), caudal (b), right lateral (c) and cranial (d) views; PVL 4054, portions of complete left humerus in caudal (e) and cranial
(f) views; KU-NM-37, proximal end of left humerus in caudal (g) and proximal (h) views. For measurements see Table 1; scale bars
are 10 mm.
982 C. A. WALKER, E. BUFFETAUT & G. J. DYKE
Table 1. Measurements of humeri (in mm) referred to the euenantiornithine Martinavis
PVL 4054
M. vincei
PVL 4059
M. vincei
PVL 4025
Martinavis sp.
PVL 4046
Martinavis sp.
PVL 4028
Martinavis sp.
KU-NM-37
Martinavis sp.
ACAP-M 1957
M. cruzyensis
Max. length 110 95.292
Width: bicipital crest to
deltoid crest
22.220.914.821
Length: deltoid crest 25.425.47.16.328
Length: medial bicipital crest 10 9.76.716.611.2
Width: pneumotricipital fossa 9.784 17.77.3
Max. width distal end 20 20 20.821.2
Max. width olecranon fossa 7.97.9 7.6
See text for details and museum acronyms.
Etymology. For M. Vince who helped to collect the
original El Brete material and was responsible for much
of its preparation (J. Bonaparte, pers. comm. 1976).
Type locality. El Brete, Maastrichtian Lecho Forma-
tion, Salta Province Argentina (Bonaparte et al. 1977;
Bonaparte & Powell, 1980; Chiappe, 1993) (Fig. 2).
Diagnosis. Euenantiornithine bird, comparable in size
to M. cruzyensis (Table 1) but with a humerus that has
a bicipital crest angled more cranially, a capital groove
with a deeper depression, and more distally enlarged
internal and external condyles (Fig. 4e, f).
Martinavis sp.
Referred specimens. PVL 4025, almost complete left
humerus lacking the ‘median ridge’ that is crushed
distally; PVL 4046, left humerus lacking its distal end;
PVL 4028, left humerus lackings its distal end; KU-
NM-37, proximal end of left humerus.
Localities. Argentina: PVL 4025 and 4046 were col-
lected from the same locality as M. vincei (J. Bonaparte
pers. comm.). USA: KU-NM-37 was collected from
Campanian sediments at Lance’s Quarry, in New
Mexico, USA (L. D. Martin, pers. comm. 1980).
Remarks. Although PVL 4025 and PVL 4028 are
smaller than the humeri referred above to either
M. vincei or M. cruzyensis (Fig. 4; Table 1), we
do not consider it prudent at present to allocate
these specimens to distinct species. In addition to
size, a number of subtle osteological differences are
nevertheless evident in comparison, not only between
these specimens, but also with ACAP-M 1957, and the
types of M. vincei (PVL 4054 and PVL 4059) (Fig. 4).
The bicipital crest of PVL 4025 is less cranially inclined
than in the other elements referred to Martinavis, the
distal extremity of the deltoid crest meets the shaft more
abruptly, no depression is present in the capital groove,
and the floor of the pneumatic fossa is depressed and
broader. PVL 4028 is similar in size to PVL 4046
(Table 1), but differs in having a shorter deltopectoral
crest and a deeper pneumatic fossa. The bicipital crest
in this specimen is also more inclined cranially than in
its counterpart PVL 4046 and the external tuberosity is
more enlarged and bulbous (Fig. 4). In comparison,
the most distinctive of these referred specimens is
KU-NM-37, from the Campanian of New Mexico
(Fig. 4). This incomplete element is indistinguishable
from other bones referred here to Martinavis; it is from
a large bird, slightly larger than the proximal part of
humerus of the first named euenantiornithine from El
Brete, Enantiornis leali (Walker, 1981; Table 1).
6. Description
Of the large sample of elements collected from El Brete,
the humerus is the most diagnostic at present and thus
is used to diagnose Martinavis. As noted above, we are
unable to match the El Brete forelimb bones with any of
the hindlimb elements already described (and named)
by Chiappe (1993) and figured by Chiappe (1996) and
Chiappe & Walker (2002). While it is certainly possible
that Martinavis may prove to be a junior synonym
of either Soroavisaurus,Lectavis or Yungavolucris
(Chiappe, 1993), the discovery of additional articulated
fossil birds will be required before this can be tested.
The general features of the Martinavis humerus ex-
emplify the morphology of this bone in Enantiornithes
in general and Euenantiornithes in particular; all of
these birds are characterized by the presence of an ‘L-
shaped’ (Walker, 1981) proximal articulation, a well-
marked depression below the caput on the cranial
surface (sulcus for the transverse ligament) and poorly
developed distal condyles (Fig. 4). In all Martinavis
specimens, as in all euenantiornithines, the head of the
humerus is concave cranially and convex dorsally; the
dorsal margin of this bone is particularly concave below
the deltopectoral crest. The shaft of the humerus lacks
marked curvature, although it is somewhat thicker and
more robust in the specimen from Cruzy (ACAP-M
1957), compared to the bones from El Brete.
The pneumatic fossa of the proximal part of the
humerus (crus dorsale fossae) in Martinavis is much
wider than in its contemporary Enantiornis (Chiappe,
1996; Chiappe & Walker, 2002) and the ventral tuber-
culum is not perforate (Figs 4, 5). Both taxa lack a pneu-
matic foramen on the proximal part of the humerus.
The deltopectoral crest of the humerus in Martinavis
is flat, broad and lacks any marked degree of cranial
curvature, while the bicipital crest is smaller, boss-like
and projected cranially. On the ventral margin of this
crest there is a small distally located fossa, likely a site
Euenantiornithine birds 983
Figure 5. Some of the skeletal elements (parts of PVL 4035
and 4020) previously referred to the El Brete euenantiornithine
Enantiornis leali (Walker, 1981; Chiappe & Walker, 2002):
proximal end of left humerus (PVL 4035) in cranial (a) and
caudal (b) views; reconstructed complete left humerus of
Enantiornis leali (PVL 4035 and 4020) in cranial (c), caudal
(d), and right lateral (e) views. Scale bars are 10 mm.
for muscle attachment (region of m. pectoralis). The
ventral tuberculum is well developed, projected caud-
ally, and does not bear a well-defined proximodistal
canal. The deltopectoral crest in Martinavis joins the
shaft smoothly, as opposed to at an angle as is the case
in Enantiornis (Walker, 1981; Chiappe, 1996; Chiappe
& Walker, 2002). The bicipital crest is more cranially
deflected in Martinavis than in Enantiornis (Fig. 5).
Distally the humerus of Martinavis is flared cranially
and has a poorly developed ventral (internal) condyle.
The ectepicondyle and entepicondyle are distinctly
rounded and lack marked tricipital grooves; between
the two distal condyles there is a deep, excavated
olecranon fossa on the caudal surface (Fig. 4). The
ventral epicondyle is enlarged, extending distally to
below the level of the dorsal and ventral condyles. The
internal condyle is not expanded and bulbous, as in
modern birds (Neornithes: Clarke & Norell, 2002).
A number of fossil eggshell fragments from the
same horizon and locality as Martinavis cruzyensis are
currently under study by Gerald Grellet-Tinner (South
Dakota School of Mines, Rapid City, South Dakota);
preliminary analysis of these fragments supports their
enantiornithine affinities, as well as the presence of
additional birds and non-avian dinosaurs at Massecaps
(Grellet-Tinner et al. unpub. data).
7. Discussion
7.a. El Brete euenatiornithines
Walker (1981) was the first to address the El Brete
collection of euenantiornithine bones, presenting a
series of osteological characters to define the taxon
Enantiornis leali (Walker, 1981, table 2). Walker
(1981) also intended to present the osteological
evidence for the existence of a new clade of Cretaceous
birds (‘Enantiornithes’), a conclusion that met with
extensive criticism in the 1980s (Steadman, 1983).
The holotype of the first of the El Brete euen-
antiornithines to be described, Enantiornis leali,is
PVL 4035 (Walker, 1981; Chiappe, 1996; Chiappe &
Walker, 2002). This is one of the very few El Brete spe-
cimens that consists of associated elements: portions
of a left humerus (Fig. 5), coracoid and scapula. The
coracoid of Enantiornis leali (PVL 4035) was figured
in cranial view by Walker (1981) alongside the humerus
(PVL 4054) which is now the holotype of Martinavis
vincei. A scapula (PVL 4039) is very similar to PVL
4035, while a carpometacarpus (PVL 4049), right
femur (PVL 4037), distal tibiotarsus (PVL 4033), and
ilium and ischium (PVL 4042) are consistent in their
size to the holotype of E. leali. Alongside these bones, a
proximal tarsometatarsus (PVL 4021, now the holotype
of Lectavis bretincola: Chiappe, 1993), a complete
right tarsometatarsus (PVL 4053, now the holotype
of Yungavolucris brevipedalis: Chiappe, 1993), and a
complete tarsometatarsus (PVL 4048) (Walker, 1981)
have also been described and await revision. We note
that PVL 4049, PVL 4037 and PVL 4033 are consistent
in size with the humeri of Martinavis.
In the early 1990s, Walker sent all materials
pertaining to his work on the El Brete collections
to L. M. Chiappe, then working at the American
Museum of Natural History in New York. Chiappe
(1991) described and figured a number of the El Brete
specimens for the first time: PVL 4048 and PVL 4021
(Walker, 1981), alongside PVL 4052 (a complete left
tarsometatarsus) and PVL 4043 (the proximal end of
right humerus). Chiappe (1992, 1993) focused on the
hindlimb morphology of these birds (contra Walker,
1981). In the context of the known morphology of
the group, Chiappe (1992) presented a discussion of
the tarsometatarsal morphology of the enantiornithine
Avisaurus, describing the anatomy of this element
based on specimens PVL 4048, PVL 4053 and PVL
4021. Chiappe (1992) also provided a sketch of PVL
4690, for the first time (Chiappe, 1992).
Chiappe (1993) published a review of known
tarsometatarsal types based again on the El Brete
collections, recognizing three taxa: Yungavolucris
brevipedalis, Lectavis bretincola and Soroavisaurus
australis. The squat tarsometatarsi from El Brete were
used by Chiappe (1993) to diagnose Yungavolucris
brevipedalis (PVL 4053 (holotype), PVL 4040, PVL
4052, PVL 4268 and PVL 4692 (referred specimens)).
Of these elements PVL 4692 is extremely fragmentary,
comprising just the distal trochlea of metatarsals II
and III; the holotype (PVL 4053) and PVL 4692 were
figured by Chiappe (1993). Lectavis bretincola was
erected by Chiappe (1993) on the basis of a single
specimen (PVL 4021), an elongate and slender asso-
ciated left tarsometatarsus and tibiotarsus. PVL 4021
was illustrated by Chiappe (1993). Finally, Chiappe
(1993) named Soroavisaurus australis on the basis
of two isolated tarsometatarsi, PVL 4690 (holotype)
and PVL 4048 (referred specimen including associated
phalanges and claws). Both of these specimens were
984 C. A. WALKER, E. BUFFETAUT & G. J. DYKE
illustrated by Chiappe (1993); they were originally
referred to the enantiornithine Avisaurus by Brett-
Surman & Paul (1985) (see also Chiappe, 1992;
Chiappe & Calvo, 1994).
All the bones of the holotype specimen of En-
antiornis leali were figured by Chiappe (1996), and
following Walker (1981), some additional specimens
were referred to this taxon: PVL 4020 (an associated
but crushed forelimb skeleton including a left scapula,
coracoid, both ends of a humerus and an imperfect ulna
as well as a right ulna and radius and proximal portion
of a carpometacarpus and digits), PVL 4039, PVL 4055
(isolated scapulae), PVL 4023, and PVL 4181 (isolated
ulnae).
To date, the most complete published compendium
of euenantiornithine anatomy is that of Chiappe &
Walker (2002), who reviewed the composition of the
entire clade drawing heavily on the El Brete specimens,
many of which were illustrated in this paper for the first
time (PVL 4698, an isolated right mandibular ramus;
PVL 4041 and 4051, series of thoracic vertebrae; PVL
4041 and PVL 4042, complete pelvises). Chiappe &
Walker (2002) also figured PVL 4025 (referred here
to Martinavis) and provided a sketch of PVL 4060 (a
proximal end of a femur). Some of this newly figured
material had been previously referred to Enantiornis
leali (PVL 4055, an isolated scapula; PVL 4023, a
complete ulna), but was not available to us for this
study. In addition, Chiappe & Walker (2002) referred
PVL 4049 (a complete carpometacarpus, also figured)
to E. leali and referred PVL 4033 and PVL 4030
(two tibiotarsi; PVL 4030 figured for the first time)
to Soroavisaurus australis.
As a result of this earlier work, we know that
at least four taxa of euenantiornithines were present
at El Brete: Enantiornis (Walker, 1981; Chiappe &
Walker, 2002), Martinavis (this paper), and at least two
of the three taxa described by Chiappe (1993). This
conservatively assumes that one of Chiappe’s (1993)
taxa could turn out to be the same bird as either
Martinavis or Enantiornis. On the other hand, as many
as six euenantiornithines may be represented in the El
Brete collections: all of the genera mentioned above
as distinct taxa, as well as an additional morphotype
identified by Walker (1981). Further discussion of this
material, as well as additional post-cranial elements
subjectively referrable to Martinavis, will form the
subject of a later paper (Walker & Dyke, unpub. data).
7.b. Massecaps euenantiornithines
Buffetaut (1998) briefly reported two euenantiornithine
bones from the Late Cretaceous Massecaps locality,
near Cruzy in southern France (see also Buffetaut,
2005). These bones, a right coracoid and left femur,
are large and were at the time the first records of
Enantiornithes from the European Upper Cretaceous.
Subsequently, additional specimens have been
described from similarly aged (late Campanian to early
Maastrichtian) strata in Provence, southern France
(Buffetaut, Mechin & Mechin-Salessy, 2000) and
from Santonian deposits in the Bakony Mountains,
Hungary ( ¨
Osi, 2007). Buffetaut (1998) noted particular
similarities between the Massecaps specimens and
Enantiornis from El Brete: the coracoid (ACAP-M
192) is almost the same size as PVL 4035 and has a
reduced acrocoracoid and robust head. Both specimens
also have a pneumatic foramen located cranially with
respect to the sternocoracoid impression (the ‘dorsal
fossa’ of Buffetaut, 1998); in ACAP-M 192 and Enan-
tiornis (PVL 4035) this foramen does not open into the
fossa. The left femur (ACAP-M 193) from Massecaps
is also very similar in size to other bones from El Brete
(Buffetaut, 1998; Chiappe, 1996); the French element
also has a well-developed trochanteric crest and is
deeply excavated on its lateral face, as described in
some of the El Brete specimens (Chiappe & Calvo,
1994; Chiappe & Walker, 2002). The clear degree of
anatomical similarity between the Massecaps and El
Brete euenantiornithines is further confirmed by the
humeri described in this paper (Fig. 4). It cannot be
excluded that the coracoid, femur and humerus from
Massecaps all belong to the same individual, although
this cannot be demonstrated other than on the basis
of their relative proportions, as they were not found in
articulation.
7.c. Distribution of euenantiornithines
Martinavis is one of very few reported Cretaceous ver-
tebrate taxa known to have had a distribution spanning
Europe, North and South America; in other words, we
have demonstrated that very similar euenantiornithine
taxa were present on both Laurasia and Gondwana in
late Campanian–early Maastrichtian times. Most other
enantiornithines, indeed Mesozoic birds in general
(Kurochkin, 2001; Chiappe & Dyke, 2002; Fountaine
et al. 2005), are known from a single locality;
just the Late Cretaceous enantiornithines Nanantius
(Queensland, Australia and the Gobi Desert, Mongolia:
Molnar, 1986; Kurochkin, 1996), Avisaurus (El Brete,
Argentina and the Two Medicine Formation, Montana:
Brett-Surman & Paul, 1985; Varricchio & Chiappe,
1995) and Martinavis (Maasecaps, France and El Brete,
Argentina) have so far been described with a distri-
bution spanning both hemispheres. Subsequent work,
however, has suggested that the Gobi Desert species of
Nanantius (N. valifanovi: Kurochkin, 1996) is instead
referrable to Gobipteryx (Chiappe, Norell & Clark,
2001), previously described from the Gobi Desert by
Elzanowski (1974, 1977) (see also Kurochkin, 2004).
The status of Avisaurus, known only from isolated
postcranial elements, is also uncertain because the El
Brete tarsometatarsi referred to this taxon (PVL 4048,
PVL 4053, PVL 4021, PVL 4690) are unassociated.
The difference in geological age between the Albian
Euenantiornithine birds 985
Nanantius eos from Australia and the Campanian
Nanantius valifanovi from Mongolia is also worth
noting and may not be suggestive of a congeneric
status. The tarsometatarsus of Avisaurus is largely
indistinguishable from similarly sized enantiornithines:
indeed, one of the specimens from El Brete referred to
Avisaurus (PVL 4048) was illustrated as an example
of variation within the El Brete collection by Walker
(1981) (and subsequently referred to Soroavisaurus
australis by Chiappe, 1993). At the time, Walker
(1981) had not intended to give a new name to this
specimen; this was done by Brett-Surman & Paul
(1985) and Chiappe (1993), despite the specimen’s lack
of association. We raise the possibility that Avisaurus,
indeed Soroavisaurus, could be junior synonyms of
Enantiornis.
Biogeographically, the occurrence of the same bird
taxon in the Late Cretaceous of Europe, South and
North America may appear surprising. However, the
presence of faunal elements with ‘Gondwanan’ affinit-
ies in the Late Cretaceous vertebrate faunas of south-
western Europe has already been reported (Buffetaut,
1989), the most convincing cases probably being those
of abelisaurid theropods (Buffetaut, Mechin & Mechin-
Salessy, 1988) and mawsoniid coelacanths (Cavin et al.
2005), both of which occur at Massecaps together with
Martinavis. Moreover, the dispersal abilities of a volant
euenantiornithine such as Martinavis were probably
good, which may further explain the wide geographical
distribution of this genus. Dispersal, even migratory
behaviour, might be envisaged for Martinavis, but such
a hypothesis can hardly be tested on the basis of fossil
evidence.
Acknowledgements. Cyril Walker thanks Jose Bonaparte
for the initial loan of El Brete material to London in the 1970s,
Larry Martin for his generosity, help and encouragement
in the initial phases of this work, and other staff of the
University of Kansas who provided support and facilities
in the 1970s (including a number of illustrations that
appeared in Chiappe & Walker, 2002). Phil Crab, Judy
Greenwood, Phil Hurst and Tim Parmenter provided a
great deal of invaluable help and support with this project
over the years. Jose Bonaparte’s visits to London were
funded by the Frank M. Chapman fund of the American
Museum of Natural History; Eric Buffetaut and Gareth Dyke
received support for this project from Enterprise Ireland’s
Ulysses Programme (2003–2004). Excavations at Massecaps
have been funded by the Centre National de la Recherche
Scientifique, the ECLIPSE programme of CNRS and the
Association Culturelle, Arch´
eologique et Pal´
eontologique de
l’Ouest Biterrois; Eric Buffetaut thanks all the participants in
the Massecaps excavations. The text and arguments presented
in this paper greatly benefited from comments provided
in review by Zbigniew Bochenski, Evgeny Kurochkin and
Jingmai O’Connor; Julia Sigwart kindly drew Figure 2.
References
BONAPARTE,J.F.&POWELL, J. E. 1980. A continental
assemblage of tetrapods from the Upper Cretaceous
beds of El Brete, northwestern Argentina (Sauropoda–
Coelurosauria–Carnosauria–Aves). M´
emoirs de la
Soci´
et´
eg
´
eologique de France 139, 19–28.
BONAPARTE,J.F.,SALFITTY,J.A.,BOSSI,G.&POWELL,J.E.
1977. Hallazgos de dinosaurios y aves cret´
acicas en la
Formaci´
on Lecho de El Brete (Salta), pr´
oximo al l´
ımite
con Tucum´
an. Acta Geologica Lilloana 14, 5–17.
BRETT-SURMAN,M.K.&PAUL, G. S. 1985. A new family of
bird-like dinosaurs linking Laurasia and Gondwanaland.
Journal of Vertebrate Paleontology 5, 133–8.
BRODKORB, P. E. 1976. Discovery of a Cretaceous bird,
apparently ancestral to the orders Coraciiformes and Pi-
ciiformes (Aves: Carinatae). Smithsonian Contributions
to Paleobiology 27, 67–73.
BRODKORB, P. E. 1978. Catalogue of fossil birds, Part
5. Bulletin of the Florida State Museum, Biological
Sciences 15, 163–266.
BUFFETAUT, E. 1989. Archosaurian reptiles with Gondwanan
affinities in the Upper Cretaceous of Europe. Ter r a N o v a
1, 69–74.
BUFFETAUT, E. 1998. First evidence of enantiornithine birds
from the Upper Cretaceous of Europe: postcranial bones
from Cruzy (H´
erault, southern France). Oryctos 1, 131–
6.
BUFFETAUT, E. 2005. Late Cretaceous vertebrates from
the Saint-Chinian area (southern France): a review of
previous research and an update on recent finds. Acta
Palaeontologica Romaniae 5, 39–48.
BUFFETAUT,E.,LELOEUFF,J.,TONG,H.,DUFFAUD,S.,
CAV I N ,L.,GARCIA,G.,WARD,D.&Association
Culturelle, Archeologique et Paleontologique deCruzy.
1999. Un nouveau gisement de vert´
ebr´
es du Cr´
etac´
e
sup´
erieur `
aCruzy(H
´
erault, Sud de la France). Comptes
Rendus de l’Acad´
emie des Sciences de Paris 328,
203–8.
BUFFETAUT,E.,MECHIN,P.&MECHIN-SALESSY, A. 1988.
Un dinosaure th´
eropode d’affinit´
es gondwaniennes dans
le Cr´
etac´
e superieur de Provence. Comptes Rendus de
l’Acad´
emie des Sciences de Paris 306, 153–8.
BUFFETAUT,E.,MECHIN,P.&MECHIN-SALESSY, A. 2000.
An archaic bird (Enantiornithes) from the Upper
Cretaceous of Provence (southern France). Comptes
Rendus de l’Acad´
emie des Sciences de Paris 331, 557–
61.
CAV I N ,L.,FOREY,P.L.,BUFFETAUT,E.&TONG,H.
2005. Latest European coelacanth shows Gondwanan
affinities. Proceedings of the Royal Society,Biology
Letters 1, 176–7.
CHIAPPE, L. M. 1991. Cretaceous birds of Latin America.
Cretaceous Research 12, 55–63.
CHIAPPE, L. M. 1992. Enantiornithine tarsometatarsi and
the avian affinities of the Late Cretaceous Avisauridae.
Journal of Vertebrate Paleontology 12, 344–50.
CHIAPPE, L. M. 1993. Enantiornithine (Aves) tarsometatarsi
from the Cretaceous Lecho Formation of northwestern
Argentina. American Museum Novitates 3083, 1–27.
CHIAPPE, L. M. 1995. The first 85 million years of avian
evolution. Nature 378, 349–55.
CHIAPPE, L. M. 1996. Early avian evolution in the southern
hemisphere: fossil record of birds in the Mesozoic of
Gondwana. Memoirs of the Queensland Museum 39,
533–56.
CHIAPPE, L. M. 2002. Basal bird phylogeny: problems
and solutions. In Mesozoic Birds: Above the Heads
of Dinosaurs (eds L. M. Chiappe & L. M. Witmer),
pp. 448–72. Berkeley: University of California Press.
986 Euenantiornithine birds
CHIAPPE,L.M.&CALVO, J. O. 1994. Neuquenornis volans,
a new Enantiornithes (Aves) from the Upper Cretaceous
of Patagonia. Journal of Vertebrate Paleontology 14,
230–46.
CHIAPPE,L.M.&DYKE, G. J. 2002. The Cretaceous radiation
of birds. Annual Reviews of Ecology and Systematics 33,
91–124.
CHIAPPE, L. M., NORELL,M.A.&CLARK, J. M. 2001. A new
skull of Gobipteryx minuta (Aves: Enantiornithes) from
the Cretaceous of the Gobi Desert. American Museum
Novitates 3346, 1–15.
CHIAPPE, L. M., SUZUKI,S.,DYKE,G.J.,WATA B E , M.,
TSOGTBAATAR,D.&BARSBOLD, R. 2006. A new
enantiornithine bird from the Late Cretaceous of the
Gobi Desert. Journal of Systematic Palaeontology 4,1
16.
CHIAPPE,L.M.&WALKER, C. A. 2002. Skeletal morphology
and systematics of the Cretaceous euenantiornithes
(Ornithothoraces: Enantiornithes). In Mesozoic Birds:
Above the Heads of Dinosaurs (eds L. M. Chiappe &
L. M. Witmer), pp. 240–67. Berkeley: University of
California Press.
CLARKE,J.A.&NORELL, M. A. 2002. The morphology
and phylogenetic position of Apsaravis ukhaana from
the Late Cretaceous of Mongolia. American Museum
Novitates 3387, 1–46.
CRACRAFT, J. 1986. The origin and early diversification of
birds. Paleobiology 12, 383–99.
ELZANOWSKI, A. 1974. Preliminary note on the paleo-
gnathous birds from the Upper Cretaceous of Mongolia.
Palaeontologica Polonica 30, 103–9.
ELZANOWSKI, A. 1977. Skulls of Gobipteryx (Aves) from
the Upper Cretaceous of Mongolia. Palaeontologica
Polonica 37, 153–65.
ELZANOWSKI, A. 1981. Embryonic bird skeletons from the
late Cretaceous of Mongolia. Palaeontologica Polonica
42, 147–76.
FEDUCCIA, A. 1980. The Age of Birds. Cambridge: Harvard
University Press.
FEDUCCIA, A. 1999. The Origin and Evolution of Birds (2nd
edition). New Haven: Yale University Press.
FEDUCCIA, A. 2006. Mesozoic aviary takes form. Proceed-
ings of the National Academy of Sciences 103,5
6.
FOUNTAINE,T.M.R.,BENTON,M.J.,DYKE,G.J.&NUDDS,
R. L. 2005. The quality of the fossil record of Mesozoic
birds. Proceedings of the Royal Society of London,
Series B (Biological Sciences) 272, 289–94.
GARCIA,G.&VALENTIN, X. 2001–2002. Les restes d’oeufs
de dinosaures dans les s´
eries continentales du chaˆ
ınon de
Saint-Chinian (Cr´
etac´
esup
´
erieur, 80–70 Ma). Bulletin
de la Soci´
et´
e d’Etude des Sciences naturelle de B´
eziers
19, 11–16.
HARRISON,C.J.O.&WALKER, C. A. 1973. Wyley i a :anew
bird humerus from the lower Cretaceous of England.
Palaeontology 16, 721–8.
KUROCHKIN, E. N. 1985. A true carinate bird from the Lower
Cretaceous deposits in Mongolia and other evidence of
early Cretaceous birds in Asia. Cretaceous Research 6,
271–8.
KUROCHKIN, E. N. 1995. Synopsis of Mesozoic birds and
early evolution of Class Aves. Archaeopteryx 13, 47–66.
KUROCHKIN, E. N. 1996. A new enantiornithid of the of the
Mongolian Late Cretaceous, and a general appraisal of
the infraclass Enantiornithes (Aves). Russian Academy
of Sciences, Special Issue, 1–50.
KUROCHKIN, E. N. 1999. A new large enantiornithid from the
Upper Cretaceous of Mongolia (Aves, Enantiornithes).
In Materials on the History of Fauna of Eurasia (eds
I. Darevskii & A. Averianov), pp. 130–41. Zoological
Institute of the Russian Academy of Sciences, St.
Petersburg (in Russian).
KUROCHKIN, E. N. 2001. New ideas on origin and early
evolution of birds. In Achievements and Problems of
Ornithology of Northern Eurasia on a Boundary of
Centuries (eds E. N. Kurochkin & I. I. Rakhimov),
pp. 68–96. Magrif, Kazan (in Russian with English
summary).
KUROCHKIN, E. N. 2004. The truth about Gobipteryx.In
Sixth International Meeting of the Society of Avian
Paleontology and Evolution, Abstracts (eds E. Buffetaut
& J. Le Loeuff), pp. 33–4. Quillan, France.
LINNAEUS, C. 1758. Systema Naturae per Regna Tria
Naturae. Holmiae, L. Salmi (10th edition).
MARTIN, L. M. 1983. The origin and early radiation of birds.
In Perspectives in Ornithology (eds A. H. Brush &
G. A. Clark Jr.), pp. 291–338. Cambridge University
Press.
MOLNAR, R. A. 1986. An enantiornithine bird from the Lower
Cretaceous of Queensland, Australia. Nature 322, 736–
8.
NESSOV, L. A. 1984. Pterosaurs and birds of the late
Cretaceous of Central Asia. Paleontological Journal 1,
47–57 (in Russian).
OLSON, S. L. 1985. The fossil record of birds. In Avi an
Biology 8(edsD.S.Farner,J.R.King&K.C.Parkes.),
pp. 79–238. New York: Academic Press.
¨
OSI, A. 2007. Enantiornithine bird remains from the Late
Cretaceous of Hungary. Oryctos (in press).
RAYNER,J.M.V.&DYKE, G. J. 2002. Evolution and origin
of diversity in the modern avian wing. In Ve r t e b ra t e
Biomechanics and Evolution (edsV.Bels,J.P.Gasc
& A. Casinos.), pp. 297–317. London: Bios Scientific
Publishers.
STEADMAN, D. W. 1983. Commentary (on Martin, 1983). In
Perspectives in Ornithology (eds A. H. Brush & G. A.
Clark Jr.), pp. 338–44. Cambridge University Press.
THULBORN, R. 1984. The avian relationship of Archaeo-
pteryx and the origin of birds. Zoological Journal of
the Linnean Society 82, 119–58.
VARRICCHIO,D.J.&CHIAPPE, L. M. 1995. A new bird from
the Cretaceous Two Medicine Formation of Montana.
Journal of Vertebrate Paleontology 15, 201–4.
WALKER, C. A. 1981. New subclass of birds from the
Cretaceous of South America. Nature 292, 51–3.
ZHANG,F.&ZHOU, Z. 2000. A primitive enantiornithine bird
and the origin of feathers. Science 290, 1955–9.
ZHANG,F.,ZHOU,Z.,HOU,L.&GU, G. 2000. Early
diversification of birds – evidence from a new opposite
bird. Chinese Science Bulletin 45, 2650–7.
... The intermediate trabecula is straight, pointed and mostly caudally oriented with a slight lateral deflection, whereas, in other enantiornithines, this process is typically proximally broad, triangular and medially curved (Supplementary Fig. 1c-f) [19,21]. The humerus is twisted such that the proximal and distal ends are expanded in different planes ( Fig. 2a and b), as in other enantiornithines [22,23]. The bicipital crest strongly projects cranioventrally, forming a bulbous cranial surface with respect to the proximal humerus. ...
... The bicipital crest strongly projects cranioventrally, forming a bulbous cranial surface with respect to the proximal humerus. A pit-shaped fossa is positioned on the ventrodistal surface of the bicipital crest, as in the stem ornithuromorph Ichthyornis [24], whereas this fossa is more cranially located in most enantiornithines [23]. The deltopectoral crest is short, less than a quarter of the humeral length, compared to one-third in similarly sized enantiornithines such as Cathayornis, Pterygornis and Shangyang. ...
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A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.
... Given the general absence of functionally informative soft tissue evidence in avialan fossils, the dispersal ability of Mesozoic avialans is even harder to estimate than modern birds, providing major challenges to biogeographic analysis of this clade. However, the distribution of Late Cretaceous taxa such as the enantiornithine Martinavis, found in North and South America and in Europe (Walker et al., 2007), if in fact all specimens have been correctly referred to a single genus, may suggest at least some taxa were able to disperse long distances, and were unrestricted in their dispersal relative to nonavialan dinosaurians. ...
Conference Paper
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The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earth’s surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately, few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the Theropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentationinduced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges.
... Given the general absence of functionally informative soft tissue evidence in avialan fossils, the dispersal ability of Mesozoic avialans is even harder to estimate than modern birds, providing major challenges to biogeographic analysis of this clade. However, the distribution of Late Cretaceous taxa such as the enantiornithine Martinavis, found in North and South America and in Europe (Walker et al., 2007), if in fact all specimens have been correctly referred to a single genus, may suggest at least some taxa were able to disperse long distances, and were unrestricted in their dispersal relative to nonavialan dinosaurians. ...
Chapter
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The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earth's surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately , few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the The-ropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentation-induced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges.
... Two enantiornithine specimens (including the holotype of Noguerornis) have also been collected from the lithographic limestones of the Hauterivian-Barremian La Pedrera de Rúbies Formation near Montsec, Spain (Lacasa-Ruiz, 1988;Sanz et al., 1997;Szwedo and Ansorge, 2015). Fragmentary enantiornithines including the holotype of Martinavis cruzyensis and the ornithothoracine Gargantuavis have been collected from late Campanian-early Maastrichtian deposits in southern France (Buffetaut et al., 1995;Buffetaut, 1998;Walker et al., 2007). In Romania, an enantiornithine nesting colony that also preserved bones has been found in the Maastrichtian Sebeş Formation (Dyke et al., 2012), and an enantiornithine humerus has been described from Upper Cretaceous deposits in the Hateg Basin . ...
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An unabated surge of new and important discoveries continues to transform knowledge of pen-naraptoran biology and evolution amassed over the last 150+ years. This chapter summarizes progress made thus far in sampling the pennaraptoran fossil record of the Mesozoic and Paleocene and proposes priority areas of attention moving forward. Oviraptorosaurians are bizarre, nonparavian pennaraptorans first discovered in North America and Mongolia within Late Cretaceous rocks in the early 20th century. We now know that oviraptorosaurians also occupied the Early Cretaceous and their unquestionable fossil record is currently limited to Laurasia. Early Cretaceous material from China preserves feathers and other soft tissues and ingested remains including gastroliths and other stomach contents, while brooding specimens and age-structured, single-species accumulations from China and Mongolia provide spectacular behavioral insights. Less specialized early oviraptorosaurians like Incisivosaurus and Microvenator remain rare, and ancestral forms expected in the Late Jurassic are yet to be discovered, although some authors have suggested Epidexipteryx and possibly other scansoriopterygids may represent early-diverging oviraptorosaurians. Long-armed scansoriopterygids from the Middle-Late Jurassic of Laurasia are either early-diverging oviraptorosaurians or paravians, and some have considered them to be early-diverging avialans. Known from five (or possibly six) feathered specimens from China, only two mature individuals exist, representing these taxa. These taxa, Yi and Ambopteryx, preserve stylopod-supported wing membranes that are the only known alternative to the feathered, muscular wings that had been exclusively associated with dinosaurian flight. Thus, scansoriopterygid specimens-particularly those preserving soft tissue-remain a key priority for future specimen collection. Dromaeosaurids and troodontids were first discovered in North America and Mongolia in Late Cretaceous rocks. More recent discoveries show that these animals originated in the Late Jurassic, were strikingly feathered, lived across diverse climes and environments, and at least in the case of dromaeosaurids, attained a global distribution and the potential for aerial locomotion at small size.
... Only a few Late Cretaceous birds have been reported from Europe and most of these were assigned to the Enantiornithes (Buffetaut et al., 2000;Walker et al., 2007;Wang et al., 2011a;Mayr, 2017). In general, isolated skeletal elements of the pelvic girdle of Mesozoic birds are very rare, which makes it all the more surprising that the fossil record of Gargantuavis mainly consists of pelvis fragments from different localities. ...
Article
We describe a well-preserved pelvis from the Maastrichtian Sanpetru Formation of the Hateg Basin in Romania. The fossil closely resembles the pelvis of Gargantuavis philoinos from the Ibero-Armorican Peninsula, but differs in a smaller size and a few morphological features. It constitutes the first record of Gargantuavis outside the Ibero-Armorican Island and is more complete than any of the previously known Gargantuavis pelves. The new fossil allows the recognition of characteristics previously unknown for Gargantuavis. These include the presence of large supratrochanteric processes, the absence of a widened midsection of the synsacrum (which indicates the absence of a glycogen body), and the absence of fusion between the pelvic bones at the level of the acetabulum. The latter two features suggest that Gargantuavis is not closely related to the Ornithurae and the taxon may even fall outside the Ornithothoraces, the clade including Enantiornithes and Ornithuromorpha. Recognition of Gargantuavis in the fauna of the Hateg Island is of particular significance, because various theropods have been described from the Upper Cretaceous of Romania. The Romanian pelvis is of similar size to Elopteryx nopcsai, which was described as avian and is based on hindlimb elements, and it also shows some similarities to the pelvis of the unusual theropod Balaur bondoc. The new fossil furthermore disproves the hypothesis that the flight capabilities of Gargantuavis were lost in an insular environment of the Ibero-Armorican Island, and raises the possibility that Gargantuavis, Elopteryx, and Balaur belong to a distinctive theropod clade of the Late Cretaceous European archipelago.
... In contrast, later avialans, such as Sapeornis (Figure 14; Provini et al., 2009), Jeholornis (Lefèvre et al., 2014, Jixiangornis (Chiappe and Meng, 2016), Confuciusornis (e.g. JME 1997/1; Chiappe et al., 1999), Enantiornithes (Walker et al., 2007), Ichthyornis (Clarke, 2004), and many modern birds ( Figure 16D) have a welldeveloped, anteromedially facing facet for the insertion of this most important flight muscle on the mediodistal part of the deltopectoral crest. Alcmonavis also shows such a marked facet on the medial side of the deltopectoral crest (Figures 3 and 16C), which is smaller than in many modern birds, but comparable in development to the facet seen in Confuciusornis, Jeholornis, Jixiangornis and Sapeornis. ...
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The Late Jurassic 'Solnhofen Limestones' are famous for their exceptionally preserved fossils, including the urvogel Archaeopteryx, which has played a pivotal role in the discussion of bird origins. Here we describe a new, non-archaeopterygid avialan from the Lower Tithonian Mö rnsheim Formation of the Solnhofen Archipelago, Alcmonavis poeschli gen. et sp. nov. Represented by a right wing, Alcmonavis shows several derived characters, including a pronounced attachment for the pectoralis muscle, a pronounced tuberculum bicipitale radii, and a robust second manual digit, indicating that it is a more derived avialan than Archaeopteryx. Several modifications, especially in muscle attachments of muscles that in modern birds are related to the downstroke of the wing, indicate an increased adaptation of the forelimb for active flapping flight in the early evolution of birds. This discovery indicates higher avialan diversity in the Late Jurassic than previously recognized.
Article
A total of 227 theropod teeth have so far been recovered from the upper Campanian Laño site (northern Iberian Peninsula). The teeth were studied for their qualitative and quantitative features. From the theropod sample found at Laño, seven morphotypes attributed to five taxa are identified: a medium to large abelisaurid (Arcovenator sp.) and four small coelurosaurians (Dromaeosauridae indet., Paraves indet., cf. Paronychodon sp. and cf. Richardoestesia sp.) Together with the ground bird Gargantuavis and a possible ornithomimosaur, the theropod fauna of Laño might be composed of two medium–large-sized non-avian theropods, four small-bodied non-avian theropods and a large terrestrial bird. This makes the Laño site the richest and most diverse latest Cretaceous theropod site in Europe. Furthermore, the Laño site and the Upper Cretaceous localities of Europe that have yielded theropod remains suggest that the medium–large-sized theropods were abelisaurids or indeterminate theropods. The small theropods are more abundant, diverse and represented by different dromaeosaurids, Paronychodon, Richardoestesia or related forms, troodontids and, probably, by other paravians. Of the birds, enantiornithines, gargantuaviids and ornithurines are also common in the European Upper Cretaceous sites. The theropod assemblage of Laño, together with the taxa of other Upper Cretaceous sites, supports the idea that several theropod dispersal events took place during the Cretaceous. This resulted in a mixture of European endemic, Asiamerican and Gondwanan forms. This study also supports the hypothesis that the intra-Maastrichtian faunal turnover that occurred in the Ibero-Armorican landmass seems to have had no apparent effect on theropods.
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The avian relationships of Archaeopteryx are assessed in terms of the 'stem-group' concept. The avian stem-group is defined, and its constituents are identified and described. Phylogenetic analysis of stem-group birds reveals that Archaeopteryx is no more closely related to modern birds than are several types of theropod dinosaurs, including tyrannosaurids and ornithomimids. Archaeopteryx is not an ancestral bird, nor is it an 'ideal intermediate' between reptiles and birds. There are no derived characters uniquely shared by Archaeopteryx and modern birds alone; consequently there is little justification for continuing to classify Archaeopteryx as a bird. Feathers are considered to be homologues or derivatives of epidermal scales (not of hairs); they probably originated as an insulating blanket in juvenile theropods, enabling them to match the activities of bigger animals, regardless of environmental temperature fluctuations. The furcula may have been present in various theropods, including allosaurids, caenagnathids (oviraptorids) and tyrannosaurids. Several possible definitions of the class Aves are examined. It is concluded that the boundary between reptiles and birds is best placed at a pronounced 'morphological gap'. This measure ensures that most animals conventionally regarded as 'birds' will be retained in the class Aves-though Archaeopteryx would be transferred to the dinosaur suborder Theropoda. This definition also ensures that birds will be distinguished from reptiles by an extensive set of osteological characters. The origin of the class Aves (as defined here) would probably coincide with the origin of avian flight; it is unlikely that Archaeopteryx can provide any direct evidence about the origin of modern avian flight, regardless of its locomotor abilities. The 'morphological gap' between reptiles and birds is not necessarily a deficiency of the fossil record; the 'gap' may be real evidence that birds originated by evolutionary saltation-and not by gradual stages. The origin of birds is not a problem to be equated with the origin of Archaeopteryx; it is a problem to be found in the 'morphological gap' that precedes the first appearance of volant birds. The concept of the 'proavis' has outlived any usefulness it might once have had, and should be abandoned.
Chapter
First published in 1983 to celebrate the centennial of the American Ornithologists' Union, Perspectives in Ornithology collects together a series of essays and commentaries by leading authorities about especially active areas of research on the biology of birds. Readers will find in this collection a useful overview of many major concepts and controversies in ornithology.
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A theropod maxilla from the Maastrichtian of Provence is referred to the family Abelisauridae. The occurrence of an abelisaurid in S France confirms the existence of Gondwanan elements in the late Cretaceous dinosaur fauna of Europe. Includes an abridged English version. -English summary