Noguerornis gonzalezi (Aves: Ornithothoraces) from the Early Cretaceous of Spain

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Noguerornis - Chiappe & Lacasa-Ruiz - Page 1
NOGUERORNIS GONZALEZI (AVES) FROM THE EARLY CRETACEOUS OF SPAIN
LUIS M. CHIAPPE
1
AND ANTONIO LACASA-RUIZ
2
1
Department of Ornithology, American Museum of Natural History, Central Park West at 79
th
Street, New York, NY 10024, USA;
2
Sección Paleontología, Institut d’Estudis Ilerdencs, Pza. La Catedral s/n, 25002 Lleida, Spain
Running Head: Noguerornis gonzalezi

Noguerornis - Chiappe & Lacasa-Ruiz - Page 2
INTRODUCTION
The first Mesozoic avian remains from the Iberian Peninsula were reported by Vidal
(1902), who mentioned the accidental destruction of a fossil bird from the Lower Cretaceous
quarry of “ La Pedrera de Meiá” (42 01’ N; 4 35’ W) in the Spanish Province of Lleida,
Catalonia (Lacasa-Ruiz, 1985). In subsequent years, this site yielded a large number of isolated
feathers (Lacasa-Ruiz, 1985; Gómez Pallerola, 1986; Kellner, this volume). However, the first
significant discovery–the skeletal remains of Noguerornis gonzalezi–was not made until the
1980’s (Lacasa-Ruiz, 1986, 1989a, b, 1991a).
The discovery of Early Cretaceous avians from Spain provided relevant new information
about the early evolution of birds, clarifying the early pattern of morphological transformation
(see Sanz et al., 1988, this volume; Chiappe, 1991, 1995a), and establishing the earliest records
of volant birds with enhanced aerodynamic specializations (Sanz et al., 1988, 1996, this volume;
Chiappe, 1995b). The significance of the spectacular specimens of Iberomesornis romerali (Sanz
and Bonaparte, 1992; Sanz et al., this volume), Concornis lacustris (Sanz and Buscalioni, 1992;
Sanz et al., 1995, this volume), and Eoalulavis hoyasi (Sanz et al., 1996, this volume) was
immediately recognized (see Cracraft, 1988; Milner, 1993; Padian, 1996); this was not the case,
however, for the less complete Noguerornis gonzalezi. Although several papers by Lacasa-Ruiz
(e.g., Lacasa-Ruiz, 1986, 1989a, b, 1991a) remarked upon the peculiarities and significance of
Noguerornis (one of the earliest known avian members), this information has remained virtually
unnoticed. In this paper, after further mechanical preparation, we provide a detailed description
of the holotype—and still unique specimen—of Noguerornis, and discuss both its relationships to
other basal birds and its contribution to our understanding of early avian evolution.
GEOLOGICAL SETTING
The Sierra del Montsec is roughly 65 km north of the town of Lleida (Catalonia),
extending approximately 50 km from east to west (Fig. 1). The rivers Noguera Pallaresa and
Noguera Ribagorzana cross the Montsec range at right angles. In the eastern region of the
Montsec range, on the eastern slope of the valley of the Noguera Palleresa, there is a famous
quarry of lithographic limestones that since 1902 has yielded numerous well-preserved fossils of
continental facies (Lacasa-Ruiz, 1991b; Martínez-Delclós, 1991a, 1995). This quarry gained
prominence as an important paleontological site when, at the end of the 19
th
century, a small
mining company started to process the fine stone for lithographic purposes. Mining engineer L.
M. Vidal (1902) was pivotal in recognizing the importance of this fossil site and reporting, along
with other workers, the first fossil findings. The quarry reported by Vidal (1902) is known as “
Las Calizas Litográficas de Santa María de Meyá” (also known as “ La Pedrera de Meiá,” “ La
Pedrera de Rúbies,” or simply “ La Pedrera” ) in reference to its proximity to the town of Santa
María de Meyá. In more recent years, a second quarry was found nearby; this second quarry has
been named “ La Cabrúa.”
Vidal (1902) proposed a Kimmeridgian (Late Jurassic) age for the lithographic limestones
of Montsec. Later studies, however, determined the age of these deposits as Early Cretaceous, but
did not arrive at a consensus regarding their precise age (Fig. 2). Whereas paleofloristic (Barale,
1973, 1991, 1995) and ostracod (Peybernés and Oertli, 1972; Brenner et al., 1974) data placed
these beds within the Late Berriasian-Early Valanginian, recent charophyte studies point to a
younger, Late Hauterivian-Early Barremian age (Martín-Closas and López-Morón, 1995).

FIGURE 1. Map indicating the area of the Montsec range within the Province of
Lleida, Catalonia (Spain), where the holotype of Noguerornis gonzalezi was
found.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 3
Peybernés (1976) defined this 50-meter thick deposit of lithographic limestones as “
calcaires lithographiques á plantes et vertébrés de La Pedrera de Rúbies” (Unit N2) and included
it within a unit named by himself as “ Calcaires á Charophites du Montsec.” This unit has also
been referred as “ La Pedrera de Rúbies Lithographic Limestones” (see Fregenal-Martínez and
Meléndez, 1995).
Rocks at “ La Pedrera” are rhythmically laminated lithographic limestones deposited in
the distal areas of a lake that developed under a warm, subtropical-semiarid climate (Fregenal-
Martínez and Meléndez, 1995). During the Early Cretaceous, the Iberian Plate was close to the
30N parallel, and this lake was in the proximity of the seashore. However, the presence of a
marine connection with the predominantly freshwater environment has not been definitively
established (Fregenal-Martínez and Meléndez, 1995).
The fossil biota yielded by the “ La Pedrera de Rúbies Lithographic Limestones” is highly
diverse (Martínez-Delclós, 1991a, 1995). The record of plants (Barale, 1991, 1995) is composed
of pteridophytes (Ferns and Equisetales), prespermatophytes (e.g., Ginkyoales, Cycadales,
Bennettitales), and spermatophytes (Coniferales and Angiospermae), along with spores of algae
and bryophytes. The fossil fauna is composed of mollusks (Martinell and Domenech, 1991),
crustaceans (Lacasa-Ruiz and Via, 1991), arachnids (Selden, 1991), abundant insects (Martínez-
Delclós, 1991b), and vertebrates. Vertebrate fossils are known primarily by the abundant “
holosteans” and teleostean fishes (Wenz, 1991a), anurans (Wenz, 1991b), non-avian reptiles
(Buscalioni and Sanz, 1991), and birds (Lacasa-Ruiz, 1989a, b, 1991b). The avian fossil remains
comprise approximately 25 specimens of isolated feathers (see Lacasa-Ruiz, 1985; Kellner, this
volume), the holotype of Noguerornis gonzalezi (Lacasa-Ruiz, 1989a), and the enantiornithine
hatchling reported by Sanz et al. (1997).
SYSTEMATIC PALEONTOLOGY
Taxonomic Hierarchy
Aves Linnaeus, 1758
Ornithothoraces Chiappe, 1995
Enantiornithes Walker, 1981
Noguerornis gonzalezi Lacasa-Ruiz, 1989
Holotype—Slab numbered LP.1702 P (collection from “ La Pedrera,” Institut d’Estudis
Ilerdencs, Lleida, Spain), including portions of both humeri, radii, and carpometacarpi, left ulna,
furcula, tibia, three trunk vertebrae, pelvis, other osseous remains, and feathers (Fig. 2).
Locality and Horizon—La Pedrera de Meiá, Sierra del Montsec, Province of Lleida, Spain. “ La
Pedrera de Rúbies Lithographic Limestones,” Lower Cretaceous, Upper Berriasian-Lower
Barremian.
Diagnosis—Noguerornis gonzalezi is diagnosed by the presence of a strongly curved humerus, a
clear autapomorphy of this taxon.
ANATOMY
Noguerornis gonzalezi is preserved on a single slab (Fig. 2). Although most bones are
incomplete, significant anatomical details are visible on both their preserved portions and the
impressions left by them on the rock. Based on furcular and humeral comparisons, Noguerornis

Noguerornis - Chiappe & Lacasa-Ruiz - Page 4
is intermediate in size between the smaller Iberomesornis (Sanz and Bonaparte, 1992) and the
larger Concornis (Sanz et al., 1995) and Eoalulavis (Sanz et al., 1996).
Vertebral Column
The most caudal thoracic vertebra and the cranial two synsacral vertebrae are preserved.
These three elements lay on their right lateral side within the pelvic remains, exposing their left
lateral sides (Figs. 2, 3, 4C).
The caudalmost thoracic vertebra shows a broad depression excavating its centrum,
although it is not clear whether this is an artifact of its preservation. A broad lateral fossa is
present in the thoracic centra of several enantiornithine taxa (Chiappe and Walker, this volume),
Confuciusornis (Chiappe et al., 1999), Ichthyornis (Marsh, 1880), and some neornithine birds
(e.g., charadriiforms, procellariiforms). The articular surfaces of the thoracic and synsacral
vertebrae are apparently amphyplatic. The spinal processes are broad and laminar, with their
craniodorsal apex projected cranially (Figs. 3, 4C). In the caudal thoracic vertebra, a small cranial
zygapophysis is preserved. The two synsacral vertebrae are fused to each other, although the
boundary between them is still visible. The spinal processes of these two elements form a
continuous spinal crest. Zygapophyses are not preserved in these synsacral vertebrae.
Thoracic Girdle and Limb
FurculaThe furcula of Noguerornis is preserved nearly complete, and exposed
apparently in ventral view. It is robust and U-shaped, having ventral and medial faces that are
nearly flat and perpendicular to each other. The interclavicular angle is approximately 46

. The
furcula bears a hypertrophied hypocleideum which, as in the enantiornithine Cathayornis (Zhou,
1995) and Eoalulavis (Sanz et al., 1996), exceeds half the length of the clavicular rami. The
hypocleideum is thin, relatively compressed, and tapers distally (Figs. 2, 3, 4B).
HumerusThe left humerus is articulated with the ulna and radius, while the right
element is disarticulated. The humerus of Noguerornis is shorter than the ulna and radius, a
condition shared by most ornithothoracines (Chiappe, 1996). It is robust and strongly curved,
with a convex dorsal margin and a concave ventral one (Figs. 2, 3, 4C). The proximal end is
better preserved in the right, disarticulated element, being exposed in its cranial aspect. In this
view, the proximal border of the head is slightly inclined dorsally (Fig. 4C). A slight depressed
area located just distal to the proximal margin is dorsally and ventrally bordered by smooth
elevated areas. As in other basal birds (e.g., Enantiornithes, Patagopteryx) and non-avian
theropods (e.g., Deinonychus), the humeral head is concave cranially, and presumably convex
caudally. There is a short bicipital area ventral to the head (Fig. 4C). The distal end is badly
preserved in both humeri; in the left element, which is exposed caudally, the olecranon fossa is
poorly developed.
UlnaOnly the left ulna is preserved, exposed in dorsal aspect. Both distal and proximal
ends are damaged. The shaft is nearly straight, round in cross-section, and uniformly broad (Figs.
2, 3). The midshaft width appears to be only slightly broader than the radial midshaft (Table I).
The papillae for the remigial feathers are absent.
RadiusThe left radius is preserved in articulation with the humerus, ulna, and
carpometacarpus; the right element is disarticulated and mostly preserved as an impression on the
slab. The radius of Noguerornis is straight, uniformly wide, and subcylindrical in cross-section
(Figs. 2, 3). The distalmost end curves slightly caudalward. The proximal end is not preserved in

Noguerornis - Chiappe & Lacasa-Ruiz - Page 5
either radii. In contrast to the condition of some Enantiornithes (Chiappe and Calvo, 1994;
Chiappe and Walker, this volume), the radial shaft of Noguerornis lacks a caudal, axial groove.
CarpometacarpusOnly the shaft and proximal portion of the carpometacarpi are
preserved. Despite previous statements (Lacasa-Ruiz, 1989a), the three metacarpals of the hand
of Noguerornis are not unfused; they are indeed fused, at least in their most proximal end (Figs.
2, 3, 4C). A semilunate carpalcorresponding to the semilunate bone of non-avian
theropodsis coosified with the metacarpals (mostly the major and alular ones), a condition
more clearly visible under ultraviolet light. The alular metacarpal is small, forming a semicircular
medial margin without a development of an extensor process (Fig. 4A). The central area of this
metacarpal possesses a round depression on its dorsal face. Articulated to the alular metacarpal of
the left element is a spine-like proximal phalanx, with the distal end missing. The major
metacarpal is broader and more robust than the minor one. These two metacarpals are firmly
united throughout their length, leaving no intermetacarpal space (Fig. 4A). The distal end is
missing in both carpometacarpi. The impression left by the most distal portion of the right
element, however, indicates that the major and minor metacarpals curve cranially (Fig. 4A) and
that, as in Enantiornithes (Zhou, 1995; Chiappe and Walker, this volume), the latter was the
longer.
Pelvic Girdle and Limb
IschiumAmong the presumable pelvic remains, only the ischium, which is exposed
dorsally, can be confidently identified (Figs. 2, 3, 4C). The ischium of Noguerornis is a laminar,
strap-like bone that gradually narrows distally. On its proximal half, this bone possesses a large,
hook-shaped process (Fig. 4A). Pending the interpretation of its position as either cranially or
caudally oriented, this process can be alternatively regarded as a large obturator process
(Chiappe, 1995b) or the proximodorsal ischiadic process of several other basal birds (e.g.,
Enantiornithes, Confuciusornis, Unenlagia, Rahonavis) (see Martin, 1995; Hou et al., 1995;
Novas and Puerta, 1997; Forster et al., 1998a, b; Chiappe et al., 1999; Chiappe and Walker, this
volume). Although the poor preservation of the ischium prevents clarification of this structure,
the fact that a proximodorsal process is widespread among basal birds and a prominent obturator
process is not makes more probable the identification of the ischiadic process of Noguerornis as
the proximodorsal ischiadic process. It is clear, on the other hand, that both ischia contact each
other on their distal halves, forming a long symphysis. This is of particular interest, as no other
Mesozoic bird has been shown to have an ischiadic symphysis. An ischiadic symphysis has not
been definitively reported for Archaeopteryx (Wellnhofer, 1974, 1993), Rahonavis (Forster et al.,
1998a, b), or Iberomesornis (Sanz and Bonaparte, 1992), and the ischia are separated from each
other in Confuciusornis (Chiappe et al., 1999), Patagopteryx (Chiappe, 1996), Ornithurae
(Marsh, 1880; Baumel and Witmer, 1993), and those enantiornithines for which data are
available (e.g., Concornis; Sanz et al., 1995). An ischiadic symphyis is also absent in
dromaeosaurid theropods (Norell and Makovicky, 1997).
TibiaThe straight limb bone perpendicular to the right humerus is interpreted as the
tibia. This interpretation is based on the fact that the bone exhibits a crest (considered the fibular
crest), and that the most distal portion is craniocaudally compressed, as is typical of avian
tibiotarsi (Figs. 2, 3). It is not possible to discern if it is a right or left element.
Feathers

FIGURE 2. Holotype of Noguerornis gonzalezi (LP.1702.P) under ultraviolet light.
Scale bar = 1
cm.

FIGURE 3. Holotype of Noguerornis gonzalezi (LP.1702.P). Abbreviations: al1,
proximal phalanx of alular digit; alm, alular metacarpal; fur, furcula; hum, humerus;
hyp, hypocleideum; isc, ischium; isp, ischiadic process (see text for interpretation);
mam, major metacarpal; mim, minor metacarpal; pc, proximal carpal; rad, radius; sv1,
first synsacral vertebra; sv2, second synsacral vertebra; tib, tibia; tv, thoracic vertebra;
uln, ulna. Scale bar = 1 cm.

FIGURE 4. Detail of carpometacarpus (A), furcula (B), and
ischium, vertebrae, and right
humerus (C) of Noguerornis gonzalezi (LP.1702.P). Scale bar
same for A-C.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 6
Two main aggregations of feathers, corresponding to wing feathers, are preserved.
Isolated coverts are also visible on the slab. The secondary remiges are directed at an angle of
70

with respect to the ulnar shaft on the left ulna. Portions of coverts are preserved cranial to the
left radius and proximal end of the left humerus, suggesting the development of a propatagium.
Unfortunately, the internal structure of these feathers is not preserved.
PHYLOGENETIC RELATIONSHIPS
The avian relationship of Noguerornis gonzalezi is unquestionably supported by the
combination of feathers with derived characters that are either exclusive to birds (e.g., U-shaped
furcula with a hypertrophied hypocleideum, ulna longer than humerus) or uncommon among
non-avian theropods (e.g., carpometacarpus). Yet the fragmentary nature of the holotype, and
only known specimen, complicates any attempt of understanding the relationships of this species
to other basa birds.
Martin (1995) placed Noguerornis within the Enantiornithes, allying it to both
Iberomesornis and Concornis. This claim was based on the purported similarity of the humeri
and furcula of these taxa, and the alleged presence of a broad distal humeral end bearing a short
articular surface (supposed to be found in Enantiornithes). The remarkable curvature of the
humerus of Noguerornis, however, is unique, and it makes this bone quite unlike that of either
Iberomesornis or Concornis. In addition, the hypocleideum of the furcula of the latter two taxa
(based on what it is known) is definitely shorter than that of Noguerornis. Whereas the furcula of
Iberomesornis differs from that of Concornis in lacking the euenantiornithine lateral excavation
(Chiappe and Calvo, 1994; Sanz et al., 1995, 1996; Chiappe and Walker, this volume), the
presence or absence of this condition remains uncertain in the available material of Noguerornis.
Furthermore, Martin’s observations of the distal end of the humerus of Noguerornis are
equivocal because the distal ends of the humeri of the only known specimen are completely
abraded, preserving no other details besides a weak olecranon fossa on the left element.
Kurochkin (1995) also supported the inclusion of the Spanish bird within Enantiornithes.
This claim was based on the presence of a “sharp-angled furcula with hypocleideum, pronounced
external and internal tuberosities of the proximal humerus, oblique-shaped distal humerus with
the distal protrusion of the internal condyle, and metacarpals fused only proximally.” Apparently,
the condition of the furcula simply refers to the presence of both a low interclavicular angle and a
hypocleideum, attributes that are clearly not exclusive to Enantiornithes within birds (Chiappe,
1996). Furthermore, Kurochkin’s (1995) observations of the humerus are not manifest in the
poorly preserved material, and whether minor (III) and major (II) metacarpals fuse to each other
only proximally is also uncertain because the distal ends of these metacarpals are not preserved
but known only from the impressions left by the right elements (Fig. 4A).
Thus, the allocation of Noguerornis within Enantiornithes, as expressed by Martin (1995)
and Kurochkin (1995), does not seem to have any evidential support. This, however, does not
mean that Noguerornisand at least certain Enantiornithesdo not share some derived
characteristics. As pointed out by Zhou (1995), the furcula of the enantiornithine Cathayornis has
a long hypocleideum, which exceeds half the length of the clavicular rami. This condition is
comparable to that of Noguerornis and the enantiornithine Eoalulavis (Sanz et al., 1996).
Likewise, the carpometacarpus of both Cathayornis and Noguerornis has a rounded medial
margin lacking an extensor process and the minor metacarpal appears to be longer than the major

Noguerornis - Chiappe & Lacasa-Ruiz - Page 7
metacarpal and slightly curved distally. These two conditions are comparable to that of other
enantiornithines (see Chiappe and Walker, this volume).
In any case, the relationships of Noguerornis to other birds should be examined on the
basis of the distribution among taxa of all the characters available for study in the Spanish bird.
In this cladistic framework (Chiappe, this volume), Noguerornis is clustered with all
Ornithothoraces by the fusion of the semilunate carpal and the metacarpals and a U-shaped
furcula with an interclavicular angle smaller than 90

. Within Ornithothoraces, the well-
developed hypocleideum and distal projection of the minor metacarpal, which extends distally
more than the major metacarpal, group Noguerornis together with Enantiornithes and
Iberomesornis (Fig. 5), although this last character is missing in the latter taxon. Noguerornis,
however, lacks several derived characters of Euenantiornithes such as the presence of a concave
central portion of the proximal margin of the humeral head, a prominent bicipital crest of the
humerus, and a longitudinal groove on the shaft of the radius (Chiappe and Walker, this volume).
The absence of a procoelous synsacrum clusters Noguerornis with Iberomesornis (Chiappe, this
volume) (Fig. 5). The sister-taxon relationship between these taxa and between them and
Euenantiornithes (Fig. 5) is weakly supported. Nevertheless, the result of Chiappe’s analysis (this
volume) suggests that together with Iberomesornis, Noguerornis is likely a close outgroup of
Euenantiornithes. Characters that appear to be plesiomorphic for Ornithothoraces, such as its
ischiadic symphysis and the subequal diameter of the ulna and radius, may indeed be
homoplastic. This is very likely the case for the ischiadic symphysis which is definitively absent
in Confuciusornis (Chiappe et al., 1999) and dromaeosaurid theropods (Norell and Makovicky,
1997).
PALEOBIOLOGY
The fragmentary nature of the single known specimen of Noguerornis gonzalezi prevents
inferring much about its lifestyle. Nevertheless, the modern proportions and general aspect of its
wing (e.g., ulna-radius longer than humerus, distal carpals fused to metacarpals) suggest that this
bird was capable of some sort of flight. In agreement with this is the presence of a U-shaped
furcula with an enlarged hypocleideum. The U-shape of the furcula of Noguerornis which is in
contrast to the boomerang shape of that of Archaeopteryx and non-avian theropodssuggests
that this element may have functioned as a spring, bending laterally during downstroke and
recoiling during upstroke, a mechanical property observed in several neornithine birds (Jenkins et
al., 1988; Bailey and DeMont, 1991). Although the functional correlation of this mechanical
characteristic is not fully understood (Bailey and DeMont, 1991), this property of the avian
furcula is essential for a postulated secondary respiratory cycle in connection with the increased
metabolic demands of flight (Jenkins et al., 1988). Likewise, the long hypocleideum of
Noguerornis may have provided a larger area for the attachment of the coracoclavicular
membrane, enlarging the area for the most cranial origin of the M. pectoralis (Olson and
Feduccia, 1979), the main flight muscle (Raikow, 1985; Dial et al., 1987, 1988), as well as
providing additional strength to the thoracic girdle as suggested by Sanz et al. (1996) for the
enantiornithine Eoalulavis. Perhaps the strongest evidence in support of the flying capabilities of
Noguerornis rests on the presence of a propatagium (Fig. 2), the largest of the wing patagia. This
feathered skinfold has been regarded as indispensable for flight (Brown et al., 1994, 1995). A
propatagium has never been reported for Archaeopteryx. Interestingly, however, a 19
th
century
sketch of the Berlin specimen shows a fold of feathers in between the humerus and the ulna-

FIGURE 5. Cladogram illustrating the phylogenetic relationships of Noguerornis
gonzalezi to other birds (see Chiappe, this volume).

Noguerornis - Chiappe & Lacasa-Ruiz - Page 8
radius (see Ostrom, 1985), suggesting that a propatagium may indeed have been present in
Archaeopteryx. Nevertheless, given the fact that this area of the Berlin specimen has not been
prepared, and also that examination of this and other specimens fails to document the presence of
a propatagium, it seems quite likely that the ‘propatagium’ of this early sketch is simply
inaccurate. Therefore, it appears that Noguerornis is the earliest bird for which a definitive avian
propatagium is known.
The occurrence of a propatagium in such an ancient bird adds to our knowledge of the
early evolution of flight. The presence of this airfoil implies that a ligamentum propatagiale was
already developed on the leading edge of the wing, between the shoulder and the carpus. The
modern avian ligamentum propatagiale fulfills a crucial role in the wing’s extension-flexion
mechanism and is essential for avoiding distortion of this surface, allowing the wing’s proper
function as an airfoil. As hypothesized by Brown et al. (1995), the ligamentum propatagiale may
also support the distal portion of the wing against drag. This modern design of the wing’s airfoil
and control appears to have been present in Noguerornis, one of the earliest known birds after
Archaeopteryx.
ACKNOWLEDGMENTS
We are grateful to N. Frankfurt and S. Copeland for preparing some illustrations, and to
D. Treon and S. Orell for editorial assistance. Support for this research was provided by grants to
L. Chiappe from the Dinosaur Society and the Guggenheim Foundation.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 9
LITERATURE CITED
Bailey, J. P., and M. E. DeMont. 1991. The function of the wishbone. Canadian Journal of
Zoology 69:2751-2758.
Barale, G. 1973. Présence du genre Frenelopsis Schenk dans les calcaires lithographiques du
Montsec, province de Lérida (Espagne). Compte Rendus de l’Académe des Sciences
227:1349-1340.
———1991.The fossil flora of the Lower Cretaceous (Berriasian-Valanginian) lithographical
limestones of Montsec (Lleida Province, Spain); pp. 39-47 in X. Martínez-Delclós (ed.), The
Lower Cretaceous Lithographic Limestones of Montsec. Ten Years of Paleontological
Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
——— 1995. The fossil flora megarests and microrests; pp. 31-38 in X. Martínez-Delclós (ed.),
Montsec and Mont-Ral-Alcover, Two Konservat-Lagerstätten. Catalonia, Spain. Field Trip
Guide Book, II International Symposium on Lithographic Limestones. Institut Estudis
Ilerdencs, Lleida, Spain.
Baumel, J. J., and L. M. Witmer. 1993. Osteologia; pp. 45-132 in J. J. Baumel, A. S. King,
J. E. Breazile, H. E. Evans, and J. C. Vanden Berge (eds.), Handbook of avian anatomy:
nomina anatomica avium, second edition. Publications of the Nuttal Ornithological Club
(23).
Brenner, P., W. Geldmacher, and R. Schroeder. 1974. Ostrakoden und Alter der Plattenkalke von
Rubies (Sierra del Montsech, Prov. Lérida, NE Spanien). Neues Jahrbuch fuer Geologie und
Palaeontologie Monatshefte 9:513-524.
Brown, R. E., J. J. Baumel, and R. D. Klemm. 1994. Anatomy of the propatagium: the great
horned owl (Bubo virginianus). Journal of Morphology 219:205-224.
———, ———, ——— 1995. Mechanics of the avian propatagium: flexion-extension
mechanism of the avian wing. Journal of Morphology 225:91-105.
Buscalioni, A. D., and J. L. Sanz. 1991. Diapsid reptiles from “ La pedrera de Rúbies.” Early
Cretaceous, Lleida, Spain; pp. 89-93 in X. Martínez-Delclós (ed.), The Lower Cretaceous
Lithographic Limestones of Montsec. Ten Years of Paleontological Expeditions. Institut
Estudis Ilerdencs, Lleida, Spain.
Chiappe, L. M. 1991. Cretaceous avian remains from Patagonia shed new light on the early
radiation of birds. Alcheringa 15(3-4):333-338.
——— 1995a. The phylogenetic position of the Cretaceous birds of Argentina: Enantiornithes
and Patagopteryx deferrariisi. Courier Forschungsinstitut-Senckenberg 181:55-63.
——— 1995b. The first 85 million years of avian evolution. Nature 378:349-355.
——— 1996. Late Cretaceous birds of southern South America: anatomy and systematics
of Enantiornithes and Patagopteryx deferrariisi; pp 203-244 in G. Arratia (ed.),
Contributions of Southern South America to Vertebrate Paleontology Münchner
Geowissenschaftliche Abhandlungen (A), vol. 30. Verlag Dr. Friedrich Pfeil,
München.
——— and J. O. Calvo. 1994. Neuquenornis volans, a new Enantiornithes (Aves) from the
Upper Cretaceous of Patagonia (Argentina). Journal of Vertebrate Paleontology
14(2):230-246.
——— Ji S.-A., Ji Q., and M. A. Norell. 1999. Anatomy and systematics of the
Confuciusornithidae (Aves) from the late Mesozoic of northeastern China. Bulletin of
the American Museum of Natural History 242: 1-89.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 10
Cracraft, J. 1988. Early evolution of birds. Nature 331:389-390.
Dial, K. P., S. R. Kaplan, G. E. Goslow, Jr., and F. A. Jenkins, Jr. 1987. Structure and neural
control of the pectoralis in pigeons: implications for flight mechanics. The Anatomical
Record 218:284-287.
———, ———, ———, ——— 1988. A functional analysis of the primary upstroke and
downstroke muscles in the domestic pigeon (Columba livia) during flight. Journal of
Experimental Biology 134:1-16.
Forster, C. A., S. D. Sampson, L. M. Chiappe., and D. W. Krause.1998a. The theropodan
ancestry of birds: New evidence from the Late Cretaceous of Madagascar. Science
279:1915-1919.
——— , ——— , ——— , ——— 1998b. Genus correction. Science 280:185.
Fregenal-Martínez, M., and N. Meléndez. 1995. Geological setting; pp. 12-24 in Montsec and
Mont-Ral-Alcover, Two Konservat-Lagerstätten. Field Trip Guide Book, II International
Symposium on Lithographic Limestones. Catalonia, Spain.
Gómez Pallerola, E. 1986. Nota preliminar sobre una pluma penna del yacimiento eocretácico de
la Pedrera de Meiá (Lérida). Boletín Geológico Minero de España 97:22-24.
Hou L., Zhou Z., L. D. Martin, and A. Feduccia. 1995. A beaked bird from the Jurassic of China.
Nature 377:616-618.
Jenkins, F. A., Jr., K. P. Dial, and G. E. Goslow, Jr. 1988. A cineradiographic analysis of bird
flight: The wishbone in starlings is a spring. Science 241:1495-1498.
Kurochkin, E. 1995. Synopsis of Mesozoic Birds and Early Evolution of Class Aves.
Archaeopteryx 13:47-66.
Lacasa-Ruiz, A. 1985. Nota sobre las plumas fósiles del yacimiento eocretácico de “ La Pedrera-
La Cabrua” en la Sierra del Montsec (Prov. Lleida, España). Ilerda 46:227-238.
——— 1986. Nota preliminar sobre el hallazgo de restos óseos de un ave fósil en el yacimiento
neocomiense del Montsec. Prov. De Lérida. España. Ilerda 47:203-206.
——— 1989a. Nuevo género de ave fósil del yacimiento neocomiense del Montsec (Provincia de
Lérida, España). Estudios Geológicos 45:417-125.
——— 1989b. An Early Cretaceous fossil bird from Montsec Mountain (Lleida, Spain). Terra
Nova 1(1): 45-46.
——— 1991a. The fossil birds from the lithographical limestones of Montsec; pp. 95-97 in X.
Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
——— 1991b. The fossiliferous outcrops of the Montsec lithographic limestones; pp. 11-14 in
X. Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
——— and L. Via. 1991. The crustacean fauna from the lithographical limestones of Montsec;
pp. 59-60 in X. Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of
Montsec. Ten Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
Marsh, O. C. 1880. Odontornithes: a monograph on the extinct toothed birds of North America.
United States Geological Exploration of the 40th Parallel. Washington: Government Printing
Office, 201 pp.
Martin, L. D. 1995. The Enantiornithes: Terrestrial birds of the Cretaceous. Courier
Forschungsinstitut-Senckenberg 181:23-36.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 11
Martín-Closas, C., and N. López-Morón. 1995. The charophyte flora; pp. 29-31 in Montsec and
Mont-Ral-Alcover, Two Konservat-Lagerstätten. Field Trip Guide Book, II International
Symposium on Lithographic Limestones. Catalonia, Spain.
Martinell, J., and R. Doménech. 1991. Malacological contents of the Montsec lithographical
limestones (Lower Cretaceous); pp. 51-52 in X. Martínez-Delclós (ed.), The Lower
Cretaceous Lithographic Limestones of Montsec. Ten Years of Paleontological Expeditions.
Institut Estudis Ilerdencs, Lleida, Spain.
Martínez-Delclós, X. 1991a. The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain, 105 pp.
——— 1991b. Insects from the lithographical limestones of the Serra del Montsec. Lower
Cretaceous of Catalonia, Spain; pp. 61-71 in X. Martínez-Delclós (ed.), The Lower
Cretaceous Lithographic Limestones of Montsec. Ten Years of Paleontological Expeditions.
Institut Estudis Ilerdencs, Lleida, Spain.
——— 1995. Montsec and Mont-Ral-Alcover, Two Konservat-Lagerstätten. Catalonia, Spain.
Field Trip Guide Book, II International Symposium on Lithographic Limestones. Institut
Estudis Ilerdencs, Lleida, Spain.
Milner, A. 1993. Ground rules for early birds. Nature 362:589.
Norell, M. A. and P. J. Makovicky. 1997. Important features of the dromaeosaur skeleton:
information from a new specimen. American Museum Novitates 3215:1-28.
Novas, F. E., and P. Puerta. 1997. New evidence concerning avian origins from the Late
Cretaceous of Patagonia. Nature 387:390–392.
Olson, S. L., and A. Feduccia. 1979. Flight capability and the pectoral girdle of
Archaeopteryx. Nature 278:247-248.
Ostrom, J. H. 1985. The Yale Archaeopteryx: the one that flew the coop; pp. 359-367 in M. K.
Hecht, J. H. Ostrom, G. Viohl, and P. Wellnhofer (eds.), The Beginnings of Birds. Eichstatt,
Freunde des Jura-Museum.
Padian, K. 1996. Early bird in slow motion. Nature 382:400-401.
Peybernés, B. 1976. Le Jurassique et le Crétacée inférieur des Pyrénées Franco-Espagnoles entre
la Garonne et la Méditerranée. Thése Doctorat de Sciences Naturelles Université Paul-
Sabatier, Toulouse, Imp. CRDP. Toulouse, 459pp.
——— and H. Oertli. 1972. La série de passage du Jurassique au Crétacé dans le Bassin sud-
pyrénéen (Espagne). Compte Rendus de l’Académe des Sciences 276:2501-2504.
Raikow, R. J. 1985. Locomotor system; pp. 57-147 in A. S. King and J. McLelland (eds.), Form
and Function in Birds, vol. 3. Academic Press, London.
Sanz, J. L., and J. F. Bonaparte. 1992. A new order of birds (Class Aves) from the Lower
Cretaceous of Spain; pp. 39-49 in K. E. Campbell (ed.), Papers in Avian Paleontology,
Honoring Pierce Brodkorb. Natural History Museum of Los Angeles County 36 (Science
Series), Los Angeles.
———, ———, and A. Lacasa. 1988. Unusual Early Cretaceous birds from Spain. Nature
331:433-435.
——— and A. D. Buscalioni. 1992. A new bird from the Early Cretaceous of Las Hoyas, Spain,
and the Early radiation of birds. Paleontology 35(4):829-845.
———, L. M. Chiappe, and A. Buscalioni. 1995. The osteology of Concornis lacustris (Aves:
Enantiornithes) from the Lower Cretaceous of Spain and a re-examination of its phylogenetic
relationships. American Museum Novitates 3133:1-23.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 12
———, ———, B. P. Pérez-Moreno, A. D. Buscalioni, J. Moratalla, F. Ortega, and F. J. Poyato-
Ariza. 1996. A new Lower Cretaceous bird from Spain: implications for the evolution of
flight. Nature 382:442-445.
———, ———, B. P. Pérez-Moreno, J. Moratalla, F. Hernández-Carrasquilla, A. D.
Buscalioni, F. Ortega, F. J. Poyato-Ariza, D. RassKin-Gutman, and X. Martínez-
Delclos. A nestling bird from the Early Cretaceous of Spain: Implications for avian
skull and neck evolution. Science 276:1543-1546.
Selden, P. 1991. Lower Cretaceous spiders from the Serra del Montsec (Spain); pp. 53-58 in X.
Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
Vidal, LL. M. 1902. Sobre la presencia del tramo Kimeridgense del Montsech y hallazgo de un
batracio en sus hiladas. Memórias de la Real Academia de Ciencias y Artes de Barcelona
4(18):263-267.
Wellnhofer, P. 1974. Das fünfte Skelettexemplar von Archaeopteryx. Palaeontographica A 147:
169-216.
——— 1993. Das siebte Exemplar von Archaeopteryx aus den Solnhofener Schichten.
Archaeopteryx 11:1-48.
Wenz, S. 1991a. Lower Cretaceous fishes from the Serra del Montsec (Spain); pp. 73-84 in X.
Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
——— 1991b. Amphibia (Anura) from the lithographical limestones of Montsec; pp. 85-87 in
X. Martínez-Delclós (ed.), The Lower Cretaceous Lithographic Limestones of Montsec. Ten
Years of Paleontological Expeditions. Institut Estudis Ilerdencs, Lleida, Spain.
Zhou Z. 1995. The discovery of Early Cretaceous birds in China. Courier Forschungsinstitut-
Senckenberg 181:9-22.

Noguerornis - Chiappe & Lacasa-Ruiz - Page 13
TABLE I. Measurements in millimeters of Noguerornis gonzalezi.
Left Right
Maximum width of proximal end of humerus 4.6 4.6
Maximum width of distal end of humerus 4.2 4.7
Maximum width of midshaft of humerus 1.8 2
Maximum length of ulna 24.3 -----
Maximum width of midshaft of ulna 1.3 -----
Maximum length of radius 23.1 23.2
Maximum width of midshaft of radius 0.9 0.9
Maximum width of proximal end of carpometacarpus 2.9 2.9
Maximum width of proximal end of alular metacarpal 1.1 1.1
Maximum width of proximal end of major metacarpal 1.2 1
Maximum width of proximal end of minor metacarpal 0.7 0.7
Maximum length of clavicular branch 9.3 10
Maximum length of hypocleideum 5.3 -----
Maximum length of trunk vertebra 1.6 -----
Maximum length of first synsacral vertebra 2 -----
Maximum length of second synsacral vertebra 2.4 -----
Length of ischium from the obturator process to distal end 10.5 -----

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