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Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought.
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A new carnivorous dinosaur from the Late Jurassic
Solnhofen archipelago
Ursula B. Go
¨
hlich
1
& Luis M. Chiappe
2
Small Late Jurassic theropod dinosaurs are rare worldwide. In
Europe these carnivorous dinosaurs are represented primarily by
only two skeletons of Compsognathus
1,2
, neither of which is well
preserved. Here we describe a small new theropod dinosaur from
the Late Jurassic period of Schamhaupten in southern Germany
3,4
.
Being exquisitely preserved and complete from the snout to the
distal third of the tail, the new fossi l is the b est-pre served
predatory, non-avian dinosaur in Europe. It possesses a suite of
characters that support its identification as a basal coelurosaur.
A cladistic analysis indicates that the new taxon is closer to
maniraptorans than to tyrannosauroids, grouping it with taxa
often considered to be compsognathids. Large portions of integu-
ment are preserved along its tail. The absence of feathers or
feather-like structures in a fossil phylogenetically nested within
feathered theropods
5,6
indicates that the evolution of these integu-
mentar y structures might be more complex than prev iously
thought.
The new Schamhaupten fossil is the second non-avian theropod
found in the laminated limestones of the Late Jurassic Solnhofen
reef archipelago of Bavaria
7
, after the discovery of the celebrated
Compsognathus nearly 150 years ago. Biostratigraphic studies of the
Schamhaupten limestones indicate that they are 151–152 million
years old
3,4,8
, and are therefore slightly older than those containing
Compsognathus and the famous bird Archaeopteryx.
Dinosauria Owen, 1842
Theropoda Marsh, 1881C
Tetanurae Gauthier, 1986
Coelurosauria Huene, 1914
Compsognathidae Marsh, 1882
Juravenator starki gen. et sp. nov.
Etymology. Jura, referring to the Bavarian Jura mountains; plus
venator (Latin), a hunter. The species name, starki, honours the
family Stark, owner of the Quarry Stark.
Holotype. JME Sch 200 (Jura-Museum Eichsta
¨
tt), a nearly complete
and articulated skeleton missing only the distal third of its tail (Fig. 1).
The strong scarring and pitting of the bone surface
9
, the lack of fusion
between sacral vertebrae, and the presence of open neurocentral
sutures
10
demonstrate that JME Sch 200 is a juvenile.
Horizon and locality. Silicified, laminated limestone, Late Jurassic,
Upper Malm, Late Kimmeridgian, Malm Epsilon 2 (setatum-
subzone), Quarry Stark, west of Schamhaupten, Southern Franconian
Alb, Bavaria, Germany (see Supplementary Information).
Diagnosis. Small basal coelurosaur (preserved length 65 cm; esti-
mated total length 75–80 cm; see Supplementary Information for
measurements) with a small number (eight) of maxillary teeth, no
premaxillary–maxillary diastema, posterior serrations on premaxil-
lary teeth, concave rostral margin of the jugal process of the
postorbital, relatively long scapula with narrowest portion at neck,
and proportionally short feet. Juravenator starki may also be diag-
nosed by the presence of an antorbital fenestra subequal in length to
the orbit and by an abbreviated deltopectoral crest of the humerus,
although these features may be related to the early ontogenetic age
of the holotype. In addition, Juravenator is unique among basal
coelurosaurs in having proximally high manual claws that taper
abruptly at midpoint, a ventrally notched premaxillary–maxillary
contact, and bow-like zygapophyses in mid-caudal vertebrae; these
features are interpreted as autapomorphies.
Description and comparisons. The skull of JME Sch 200 is propor-
tionally large (Fig. 1). It has a moderately long rostrum, elliptical
external nares bordered by the premaxilla and nasal, a big antorbital
fossa largely perforated by an antorbital fenestra and a small
maxillary fenestra, round orbits, a flat cranial roof, and teeth lacking
anterior serrations (Fig. 2). The premaxilla bears three, perhaps
four, teeth
the penultimate one posteriorly serrated (Fig. 1). The
maxillary teeth are more recurved than the premaxillary ones. The
lacrimal has the shape of an inverted ‘L. The jugal is slender with a
well-developed postorbital ramus and a tapering subtemporal ramus
that ends shortly behind the base of the latter. The frontal is large and
it participates extensively of the supratemporal fenestra. The parietal
is one-third to one-quarter the length of the frontal. The frontal
ramus of the T-shaped postorbital is slightly longer than the
squamosal ramus and shorter than the jugal ramus. The lower jaw
of Juravenator lacks a mandibular foramen, as in the compsog-
nathids
11
Compsognathus
1
, Sinosauropteryx
12
, Huaxiagnathus
13
and
Scipionyx
14
and other basal coelurosaurs such as tyrannosauroids,
and its teeth
probably not more than 11
extend caudally to nearly
the end of the upper dentition.
There are eight to ten cervical vertebrae. These have short and
low neural spines and, as in compsognathids
1,12,13
, extremely long,
hair-like ribs (Fig. 1). The trunk is composed of 13 dorsal vertebrae
with distally expanded neural spines, another synapomorphy of
compsognathids
11–13,15
. The tail is extremely long
comparisons
with Sinosauropteryx indicate that the 44 caudal vertebrae preserved
in JME Sch 200 represent about two-thirds of the complete tail. Such
an elongated tail is comparable to the tail of Sinosauropteryx and
longer than in most other theropods
16
. The caudal centra are
elongated and very similar throughout the tail. Their length remains
more or less constant until the 17th caudal, when the length of the
centra starts increasing. The transition point is around the 14th to
15th vertebra. The short zygapophyses of the middle caudals have a
uniquely hooked morphology (Fig. 1). The chevrons are elongate and
rod-like shaped; these bones decrease in length gradually towards the
distal end of the tail.
The scapula is slender and elongate (its length is about ten times its
width at mid-shaft and 80% of the length of the femur). This bone
has a prominent and subtriangular acromion and a scapular blade
LETTERS
1
Department for Geo- and Environmental Sciences, Section Paleontology, University of Munich, Richard-Wagner-Strasse 10, D-80333 Munich, Germany.
2
The Dinosaur Institute,
Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California 90007, USA.
Vol 440|16 March 2006|doi:10.1038/nature04579
329
© 2006 Nature Publishing Group
that gradually expands towards its tip. The glenoid is rimmed and
directed caudally. The forelimb is 50% of the length of the hindlimb
(measured along their longest digit and including their correspond-
ing claws)
Juravenator has the longest forelimb among compsog-
nathids. The deltopectoral crest of the humerus is proximodistally
very short and triangular in shape. The radius and ulna are straight
and about two-thirds the length of the humerus. Metacarpal I is
about 40% of the length of metacarpal II but of about the same width.
Metacarpal III is about half the width of metacarpal II and 75% of its
length. The hand of Juravenator carries three robust and clawed digits
(Fig. 1) with two (I), three (II) and four (III) phalanges. Digit I is the
shortest and digit II the longest. The pelvis consists of a low and
straight ilium with rounded and squared-off anterior and posterior
ends, respectively. The other elements of the pelvis are of difficult
interpretation. The hindlimbs are robust. The femur is 10% shorter
than the tibia, which is similarly shorter than the foot (metatarsal III
and digit including claw). Metatarsal III is the longest, followed by
metatarsals IVand II. Likewise, pedal digit III is the longest, followed
by digits IV, II and I; the phalangeal formula of these digits is 2-3-4-5.
Soft tissue is preserved along the tibiae, and particularly between
the 8th and the 22nd caudal vertebrae, where it defines the outline of
the tail. The latter section allows observation of the skin surface and
other soft parts (Fig. 3). The integument of Juravenator is formed of
uniformly sized, smooth tubercles (about 15 tubercles per 25 mm
2
of preserved tissue) similar in appearance to the small, conical and
non-imbricated tubercles of many other non-avian dinosaurs
17,18
.An
array of feathers has been discovered among non-avian coeluro-
saurs
6
. However, the absence of either feathers or skin follicles
associated with the preserved integument of Juravenator indicates
that at least the central portion of the tail of this coelurosaur was
devoid of plumage. The remaining soft tissue is represented by a
series of fibres ventral to the haemal arches of the 10th to 14th caudals
and parallel to the axis of the tail. These fibres probably represent
tendons of the hypaxial musculature and ligaments of the tail
19
,as
interpreted for similar soft parts associated with the skeleton of
Scipionyx
14
, although they could also correspond to bundles of
subcutaneous collagen fibres
20
.
A cladistic analysis of 35 theropod taxa (Supplementary Infor-
mation) clusters Juravenator with a diversity of other basal, small-
bodied coelurosaurs of Late Jurassic to Early Cretaceous age. When the
analysis is conducted with the exclusion of largely incomplete taxa,
Juravenator nests together with compsognathids such as Compsog-
nathus, Sinosauropteryx and Huaxiagnathus (Fig. 4). This condensed
analysis recovers a monophyletic Compsognathidae and supports the
placement of Juravenator within this clade.
The discovery of feathery integumentary coverings in a variety
of coelurosaurs (for example, tyrannosauroids, compsognathids,
therizinosauroids, oviraptorosaurs, alvarezsaurids and dromaeo-
saurids) has cemented the notion that feathers are a synapomorphy
of this entire clade
5,6
. Thus, the absence of feathers in Juravenator,a
Figure 1 | Holotype of Juravenator starki. a, Specimen photographed under
normal light. b, The presence of ‘hair-like’ cervical ribs (inset 1) is
synapomorphic of Compsognathidae. The proximally high manual claws
that taper abruptly at their midpoint (inset 2) and bow-like zygapophyses of
mid-caudal vertebrae (inset 3) are regarded as autapomorphies of
Juravenator starki. The serrated premaxillary teeth (inset 4) also distinguish
this taxon from most other basal coelurosaurs. Abbreviations: ca, calcaneus;
co, coracoid; cv, cervical vertebrae; dv, dorsal vertebrae; fe, femur; fi, fibula;
ha, haemal arches; hu, humerus; il, ilium; mI, metacarpal I; mII,
metacarpal II; ra, radius; sc, scapula; st, soft tissue; ti, tibia; ul, ulna; I–IV,
pedal digits I–IV; V, metatarsal V.
LETTERS NATURE|Vol 440|16 March 2006
330
© 2006 Nature Publishing Group
Figure 2 | Skull and mandible of Juravenator starki. a, Specimen
photographed under ultraviolet light. b, As reconstructed (shaded areas
show missing portions). Abbreviations: an, angular; aofe, antorbital
fenestra; d, dentary; en, external naris; f, frontal; itfe, infratemporal fenestra;
j, jugal; l, lacrimal; m, maxilla; mfe, maxillary fenestra; n, nasal; or, orbit; p,
parietal; pm, premaxilla; po, postorbital; qj, quadratojugal; sq, squamosal;
sa, surangular.
Figure 3 | Integument of Juravenator starki. a, Specimen photographed under ultraviolet light. b, Specimen photographed under normal light.
Abbreviations: c9, c11 and c13, caudal vertebrae 9, 11 and 13.
NATURE|Vol 440|16 March 2006 LETTERS
331
© 2006 Nature Publishing Group
taxon otherwise nested within feathered coelurosaurs, is noteworthy
(Fig. 4). The extent to which feathers covered the body of these
non-avian dinosaurs is not well known for some taxa (for example,
the tyrannosauroid Dilong
21
, the therizinosauroid Beipiaosaurus
22
,
and the alvarezsaurid Shuvuuia
6,23
) but complete specimens of
Sinosauropteryx
12,16
, the oviraptorosaur Caudipteryx
23
, and several
dromaeosaurids
24–26
indicate that the body of these animals was for
the most part feathered. The fact that Juravenator lacks any evidence
of feathers in portions of integument otherwise feathered in these
coelurosaurs indicates that these animals may have differed greatly in
the extension of their feathery covering. However, the role of
ontogeny and seasonality in the development of the plumage of
these dinosaurs remains uncertain, and the possibility cannot be
ruled out that feathers evolved more than once or became lost in taxa
such as Juravenator (Fig. 4).
The exquisitely preserved skeleton of Juravenator starki is the most
complete non-avian theropod so far discovered in Europe, adding to
the diversity of dinosaurs from this continent and in particular to the
meagre record of Late Jurassic small theropods
27
. Its discovery sheds
light on a poorly known segment of coelurosaur history and indicates
that the evolution of feathers in theropods might have been more
complex than previously envisaged.
Received 1 September 2005; accepted 10 January 2006.
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Supplementary Information is linked to the online version of the paper at
www.nature.com/nature.
Acknowledgements We thank H. Weiss and K.-D. Weiss for discovery of the
specimen, P. Vo
¨
lkl for its preparation, H. Tischlinger and G. Janssen for
photography, M. Ko
¨
lbl-Ebert and F. Stark for access to the specimen, and E. Frey,
D. Goujet, S. Hwang, R. Leinfelder, O. Rauhut, M. Ro
¨
per, G. Viohl, P. Wellnhofer
and W. Werner for providing access to specimens, for logistics, and/or for
discussions. This research was made possible by the Humboldt Foundation, and
was also supported by the Jurassic Foundation, European Commission’s
Research Infrastructure Action-Synthesys Program, Antorchas Foundation,
Bavarian State Collection for Paleontology and Geology, Department for Geo-
and Environmental Sciences (Munich University), DFG, Jura Museum, and
Natural History Museum of Los Angeles County.
Author Information Reprints and permissions information is available at
npg.nature.com/reprintsandpermissions. The authors declare no competing
financial interests. Correspondence and requests for materials should be
addressed to L.M.C. (chiappe@nhm.org).
Figure 4 | Strict consensus cladogram. The eight most parsimonious trees
(length 497, consistency index 0.45, retention index 0.65) for 28 theropod
taxa, including Juravenator starki and 189 variables, are shown (see
Supplementary Information). In spite of lacking feathers in the preserved
integumentary portions, Juravenator starki is grouped together with
coelurosaur clades known for having feathery coverings
6
. Plumulaceous
and/or pennaceous feathers have been discovered in taxa assigned to
Tyrannosauroidea (namely Dilong
21
; in this cladogram, tyrannosauroids are
represented by the more advanced Tyrannosaurus and Albertosaurus),
Compsognathidae (namely Sinosauropteryx
12,16
), Alvarezsauridae (namely
Shuvuuia
23
), Oviraptorosauria (namely Caudipteryx
24
), Dromaeosauridae
(namely Microraptor
25
and Sinornithosaurus
26
) and Aves (namely
Archaeopteryx and Confuciusornis)
28
.
LETTERS NATURE|Vol 440|16 March 2006
332
... During the last three decades, newly discovered theropods have dethroned Compsognathus from the iconic status of the "smallest dinosaur" (Xu et al., 2000). Furthermore, other taxa have been included in the compsognathid lineage or have been suggested to be members of the same coelurosaurian grade: Sinosauropteryx (Chen et al., 1998;Chen & Currie, 2001); Scipionyx (see Dal Sasso & Maganuco, 2011); Huaxiagnathus (Hwang et al., 2004); Mirischia (Naish et al., 2004); Juravenator (Göhlich & Chiappe, 2006); Sinocalliopteryx (Ji et al., 2007;Xing et al., 2012); and Xunmenglong (Xing et al., 2019). A specimen referred to Sinosauropteryx by Currie & Chen (2001), NGMC 2124, differs in several features from the former and represents a distinct taxon (Longrich, 2002). ...
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Laguna Verde es un lago hipersalino de 15 km2 ubicado al interior de una cuenca endorreica, a 4000 metros sobre el nivel del mar, en la cordillera andina de Atacama (Chile). Durante el año 2010, se descubrió una carcasa de Puma concolor envuelta en una costra formada por precipitación salina en gran parte del cuerpo, fue descubierta en el borde oriental de esta laguna. El espécimen actualmente se exhibe en el Museo Regional de Atacama. Para el presente estudio se procedió a caracterizar este ejemplar y las evaporitas asociadas, con la finalidad de definir las condiciones relacionadas con su deceso, además de discernir los procesos tafonómicos llevados a cabo sobre los restos, teniendo en consideración tanto las características del medio hipersalino como las del propio ambiente. Finalmente, se contrastó este caso con localidades de características similares en otras partes del mundo e incluso se comparó con paleoambientes del Mesozoico representados en afloramientos con el objetivo de lograr un mejor entendimiento de los procesos que imperaron durante las primeras fases de fosilización.
... Tianyulong confuciusi (Heterodontosauridae) opisan na osnovu ostataka pronađenih u Kini koji je ţivio prije 158,5 miliona godina (Zheng et al., 2009), Juravenator starki (Compsognathidae) koji je pronađen u Njemačkoj, a za kojeg se smatra da je ţivio prije 152-151 milion godina (Göhlich & Chiappe, 2006) i Sciurumimus albersdoerferi (Megalosauroidea) opisan na osnovu ostataka iz Njemačke koji je ţivio prije između 15,1-150,8 miliona godina (Rauhut et al., 2012). ...
... i) gornjoj juri prije između (168?)164-152 miliona godina (Xu & Zhang, 2005). Također Anchiornis huxleyi (Troodontidae) pronađen u Kini, koji je ţivio prije između 161-151 milion godina te Tianyulong confuciusi (Heterodontosauridae) opisan na osnovu ostataka pronađenih u Kini koji je ţivio prije 158,5 miliona godina (Zheng et al., 2009), Juravenator starki (Compsognathidae) koji je pronađen u Njemačkoj a za kojeg se smatra da je ţivio prije 152-151 milion godina (Göhlich & Chiappe, 2006) i Sciurumimus albersdoerferi (Megalosauroidea) opisan na osnovu ostataka iz Njemačke koji je ţivio prije između 15,1-150,8 miliona godina (Rauhut et al., 2012). ...
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U višegodišnjim zoološkim istraživanjima Bosne i Hercegovine autori, a posebno kustos ornitolog Dražen Kotrošan, su sakupili i značajan broj podataka o biodiverzitetu ptica. Spoznate činjenice, uz konstatacije o brojnim taksonomskim i nomenklaturnim promjenama date skupine u nizu publiciranih radova dovele su i do specifične obaveze zvanične aktuelizacije spomenutih podataka, osobito nakon zaključka Vijeća Odsjeka za biologiju Prirodno-matematičkog fakulteta Univerziteta u Sarajevu da prof. dr. Suvad Lelo bude odgovorni nastavnik na nastavnom predmetu (Bio)Sistematika hordata od akademske 2012/2013. godine (na prijedlog dotadašnjeg odgovornog nastavnika prof. dr. Rifat Škrijelj na čemu mu se i ovom prilikom javno zahvaljujemo). Kao zaduženi nastavnik za interpretaciju aktuelne biosistematike ptica dr. Lelo je oformio ekipu, autore ove knjige, koja je priredila rukopis (skriptu predavanja iz ornitologije) da bi obezbijedili studenskoj populaciji adekvatan prijegled podataka o bosanskohercegovačkoj i svjetskoj ornitofauni. Neophodno je istaći da je ovo prva ornitološka knjiga pripremljena u cilju edukacije studenata biologije od osnivanja Prirodno-matematičkog fakulteta Univerziteta u Sarajevu, a koja je proistekla od bosanskohercegovačkih autora. Do sada, skoro pola vijeka, generacije studenata biologije na Prirodno-matematičkom fakultetu u Sarajevu kao osnovnu literaturu iz oblasti sistematike kičmenjaka koristile knjigu prof. dr. Aleksandra Aleksopula „Zoologija kičmenjaka: morfologija, evolucija, ekologija, privredni značaj i sistematika kičmenjaka“ objavljene 1963. godine u Beogradu. Na kraju, ovu knjigu posvećujemo najznačajnijem poznavaocu bosanskohercegovačke ornitofaune, negdašnjem kustosu Zemaljskog muzeja Bosne i Hercegovine u Sarajevu – Otmaru Reizeru (O. Reiser: 1861.-1936.). O. Rajzer je kao kustos ornitolog radio od 1887. do 1914. godine pri čemu je utemeljio bosanskohercegovačku ornitologiju.
... The faunal assemblage of the Solnhofen Archipelago comprises an extremely diverse array of invertebrates and vertebrates, often showing a spectacular preservation, which made these Upper Jurassic Plattenkalk deposits world famous (especially those of the southern Franconian Alb). Unsurprisingly, terrestrial and aerial vertebrates are more rarely found than marine ones but over the last centuries, numerous specimens have been discovered, including exquisitely preserved rhynchocephalians, squamates, atoposaurid crocodyliforms, theropod dinosaurs, early avialians, and pterosaurs (Wellnhofer 1970(Wellnhofer , 1975(Wellnhofer , 2008bOstrom 1978;Göhlich and Chiappe 2006;Rauhut et al. 2012Rauhut et al. , 2019Frey and Tischlinger 2015;Tischlinger and Rauhut 2015). Among these, pterosaurs represent the most abundant reptile group and in total more than 500 pterosaur specimens are known . ...
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Pterodactylus from the uppermost Jurassic of southern Germany represents one of the most iconic pterosaurs, due to its status of being the first member of the Pterosauria to have been described and named. During the early phase of pterosaur research, Pterodactylus was a wastebasket taxon containing dozens of sometimes distantly related assigned species. Decades later, a comprehensive revision of the genus significantly reduced the number of species. To date, only one species remains in the genus, Pterodactylus antiquus , although the referral of several specimens to this taxon and the taxonomic relationships of them is still debated. Thus far, the genus has been only reported from the Upper Jurassic Plattenkalk deposits of Bavaria, and all of these occurrences are Tithonian in age. Here we describe the first record of Pterodactylus from the Torleite Formation near Painten (Bavaria), which represents the first occurrence of the genus from the Kimmeridgian. The specimen is a complete, articulated and exquisitely preserved skeleton of a small-sized individual. Aside from its old geological age, it is a typical representative of the genus, greatly resembling other specimens from younger strata. Certain characters, such as the overall size, skull length, relative orbit size, and phalangeal formula indicate that the specimen from Painten represents a juvenile to young subadult individual, an ontogenetic stage rarely found among Pterodactylus specimens. The find significantly expands the temporal range of the taxon and represents one of the best-preserved specimens of the genus reported so far.
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The Late Jurassic 'Solnhofen' Plattenkalk deposits of Bavaria are widely known as one of the most productive fossil Lagerstätten worldwide, having produced innumerable specimens of well-preserved marine protists, algae, invertebrates, and vertebrates, as well as a smaller number of terrestrial plants and vertebrates (e.g.
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Everybody knows many names of animals and plants, but very few have the slightest idea about how scientists go about naming groups of biological organisms (called “taxa”) and how these names are applied to these groups. Yet, with the explosion in our knowledge of biodiversity over the last three centuries (about 1.5 million species have been named, so about as many groups of species could potentially be named), an efficient nomenclatural system is of critical importance. A good nomenclatural practice is also of great societal importance given that it is required to fight the rapid erosion of biodiversity linked with the explosion of human populations in the last centuries. The system currently used by most practicing systematists (the biologists who describe and classify the biodiversity), known as rank-based nomenclature, harks back to the works of Linnaeus in the mid-18th century and the Strickland code, which was inaugurated in 1843. When Linnaeus proposed his system, most scientists were creationists and fixists, whereas modern biology has provided ample proof that Life has been evolving on Earth for more than 3 billion years. It is thus not unexpected that a growing number of scientists find rank-based nomenclature inadequate. This problem is linked to the fact that rank-based nomenclature aims at not delimiting taxa precisely, a goal that is arguably opposite to that of most other sciences, such as geology, chemistry and geography, and which hampers our ability to communicate efficiently about taxa. Consequently, a group of scientists has developed a new code of biological nomenclature based on new principles, called phylogenetic nomenclature. This new code, called the PhyloCode, took effect in April 2020. This book seeks to describe the history of how groups of animals and plants have been named, starting with the prehistory but focusing on the last three centuries. More importantly, it describes the underlying events and issues that have shaped this history, such as developments in systematics, evolutionary biology and phylogenetics. It outlines the current controversies and challenges facing biological nomenclature in the 21st century
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Following an investigation into the hypothesis that the iconic Berlin specimen of Archaeopteryx fossilized in nesting position, which led to the discovery not only of its association with soft eggs and several hatchlings, but also similar findings in a second Archaeopteryx specimen, an attempt to characterize the entire Berlin specimen nest and estimate its number of eggs is reported here. The Berlin specimen arranged and brooded its eggs on the ground. Its clutch size appears to have exceeded one hundred eggs. Egg littering found not only in its fossil bed but also in the sediment layer immediately above it, inclusively with evidence that a subsequent generation nested over the specimen, is consistent with repeated usage of a ground nesting site. All Archaeopteryx specimens fossilized in different views of a similar pose that is compatible with a nesting posture, and evidence of eggs of consistent size with the 2D outlines of 3D flattened eggs is present not only in the Berlin, Teylers, Thermopolis and Maxberg specimens, but also in the isolated Archaeopteryx feather fossil. In addition, egg and hatchling littering are present in the Berlin, Teylers and isolated Archaeopteryx feather fossils. Taken together, these findings are indicative of colonial ground nesting behavior by Archaeopteryx in Solnhofen. Egg littering, eggs dorsal to the Berlin specimen torso and limb rotations in the London and Thermopolis Archaeopteryx specimens can all be explained by nesting in reentrances located at the margins or in sand banks of marine lagoons in Solnhofen, which would have been flooded, causing the subsequent collapse of the nest and the still-life preservation of its content. The discovery of colonial ground nesting in a winged Jurassic bird relative favors the evolution of birds from the ground up and suggests that wings and their elongated feathers were primarily associated with ground nest protection and only secondarily with flight.
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The skin is a barrier between the internal and external environment of an organism. Depending on the species, it participates in multiple functions. The skin is the organ that holds the body together, covers and protects it, and provides communication with its environment. It is also the body's primary line of defense, especially for anamniotes. All vertebrates have multilayered skin composed of three main layers: the epidermis, the dermis, and the hypodermis. The vital mission of the integument in aquatic vertebrates is mucus secretion. Cornification began in apmhibians, improved in reptilians, and endured in avian and mammalian epidermis. The feather, the most ostentatious and functional structure of avian skin, evolved in the Mesozoic period. After the extinction of the dinosaurs, birds continued to diversify, followed by the enlargement, expansion, and diversification of mammals, which brings us to the most complicated skin organization of mammals with differing glands, cells, physiological pathways, and the evolution of hair. Throughout these radical changes, some features were preserved among classes such as basic dermal structure, pigment cell types, basic coloration genetics, and similar sensory features, which enable us to track the evolutionary path. The structural and physiological properties of the skin in all classes of vertebrates are presented. The purpose of this review is to go all the way back to the agnathans and follow the path step by step up to mammals to provide a comparative large and updated survey about vertebrate skin in terms of morphology, physiology, genetics, ecology, and immunology.
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A new, large compsognathid theropod, Huaxiagnathus orientalis gen. et sp. nov., from the Early Cretaceous Yixian Formation deposits of Liaoning Province, People's Republic of China is described. The holotype specimen is nearly complete, lacking only the distal portion of the tail. It is the second largest theropod taxon discovered from Jehol Group sediments. Like all compsognathids, Huaxiagnathus has short forelimbs and a relatively unspecialised coelurosaur body plan. Previously, fairly complete skeletons existed for only two small‐bodied taxa of compsognathids, Compsognathus longipes from the Late Jurassic of Western Europe and Sinosauropteryx prima, also from the Yixian. The phylogenetic position of Huaxiagnathus orientalis was analysed using an extensive matrix of theropod characters from many taxa. Huaxiagnathus orientalis fell out at the base of the Compso‐gnathidae, as it lacks the forelimb adaptations of more derived compsognathids. The addition of Huaxiagnathus and the two other compsognathid species to our data matrix resulted in the placement of Compsognathidae near the base of Maniraptora. Furthermore, Alvarezsauridae, Paraves, and a monophyletic Therizinosauroidea + Oviraptorosauria clade fall out in an unresolved trichotomy in the strict consensus of our most parsimonious trees.
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Closure of neurocentral sutures in the crocodylian vertebral column follows a distinct caudal to cranial sequence during ontogeny. The sutures in most caudal vertebrae are fully closed at hatching, but closure of remaining sutures occurs later in ontogeny. Closure of cervical sutures is a consistent indicator of morphological maturity in Alligator mississippiensis, Alligator sinensis, Osteolaemus tetraspis, and Crocodylus acutus; the final transformation is the closure of the axial neurocentral suture, which occurs after the closure of the axis-odontoid suture. Because these transformations occur near the end of ontogeny in all three taxa, regardless of maximum size, closure of these sutures is a size-independent criterion of maturity; however, it is not certain if suture closure indicates the stoppage of growth. These transformations are readily identifiable in fossils, permitting the objective characterization of maturity in fossil crocodylians and possibly at least some of their closer extinct relatives.
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■ Abstract Until recently, most knowledge of the early history of birds and the evolution of their unique specializations was based on just a handful of diverse Meso- zoic taxa widely,separated in time and restricted to marine,environments. Although Archaeopteryxis still the oldest and only Jurassic bird, a wealth of recent discoveries combined,with new phylogenetic analyses have documented,the divergence of a number of lineages by the beginning,of the Cretaceous. These and younger,Cretaceous fossils have filled much,of the morphological,chasm,that existed between,Archaeopteryxand its living counterparts, providing insights into the evolutionary development of feathers and other important,features of the avian flight system. Dramatic new,perceptions of the life history, growth and development of early birds have also been made possible by the latest data. Although no primitive birds are known,to have survived,beyond the end of the Cretaceous, the present fossil record provides no evidence for a sudden disappearance. Likewise, a Mesozoic origin for extant birds remains controversial.
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Dromaeosaurids, despite their notoriety, are poorly characterized meat-eating dinosaurs, and were previously known only from disarticulated or fragmentary specimens. Many studies have denied their close relationship to birds. Here we report the best represented and probably the earliest dromaeosaurid yet discovered, Sinornithosaurus millenii gen. et sp. nov., from Sihetun, the famous Mesozoic fish-dinosaur-bird locality in China. Sinornithosaurus not only greatly increases our knowledge of Dromaeosauridae but also provides evidence for a filamentous integument in this group. It is remarkably similar to early birds postcranially. The shoulder girdle shows that terrestrial dromaeosaurids had attained the prerequisites for powered, flapping flight, supporting the idea that bird flight originated from the ground up. The discovery of Sinornithosaurus widens the distribution of integumentary filaments among non-avian theropods. Phylogenetic analysis indicates that, among known theropods with integumentary filaments or feathers, Dromaeosauridae is the most bird-like, and is more closely related to birds than is Troodontidae.
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Definitive non-avian dinosaur embryos, those contained inside fossil eggs, are rare. Here we describe the first known unequivocal embryonic remains of sauropod dinosaurs—the only known non-avian dinosaur embryos from Gondwana—from a nesting found in the Upper Cretaceous stage of Pagagonia, Argentina. At this new site, Auca Mahuevo, thousands of eggs are distributed over an area greater than 1 km sq. The proportion of eggs containing embryonic remains is high: over a dozen in-situ eggs and nearly 40 egg fragments incasing embryonic material were recovered. In addition to bone, these specimens contain large patches of fossil skin casts, the first definite portions of integument ever reported for a non-avian dinosaur embryo. As morphology of the eggs enclosing these osseous and integumentary remains is identical, we propose that these specimens belong to the same sauropod species. This discovery allows the confident association of the megaloolithid type of dinosaur eggshell with sauropod dinosaurs.
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A spectacular pair of Sinosauropteryx skeletons from Jurassic-Cretaceous strata of Liaoning in northeastern China attracted worldwide notoriety in 1996 as the first dinosaurs covered with feather-like structures. Sinosauropteryx prima is important not only because of its integument, but also because it is a basal coelurosaur and represents an important stage in theropod evolution that is poorly understood. Coelurosauria, which includes (but is not limited to) dromaeosaurids, ornithomimosaurs, oviraptorosaurs, troodontids, and tyrannosaurids, formed the most important radiation of Cretaceous carnivorous dinosaurs in the Northern Hemisphere. It also includes Aves. Sinosauropteryx prima has a number of characters that were poorly preserved in known specimens of the closely related Compsognathus longipes from Europe. These include the longest tail known for any theropod and a three-fingered hand dominated by the first digit, which is longer and thicker than either of the bones of the forearm. Both specimens have a thick coat of feather-like structures, which seem to be simple branching structures. The claim that one skeleton of Sinosauropteryx has preserved the shape of the liver is unsupportable, if only because the fossil had collapsed into a single plane, which would have distorted any soft, internal organs.
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This revised edition of this book continues in the same vein as the first but encompasses recent spectacular discoveries that have continued to revolutionize this field. A thorough scientific view of current world research, the volume includes comprehensive coverage of dinosaur systematics, reproduction, and life history strategies, biogeography, taphonomy, paleoecology, thermoregulation, and extinction. It contains definitive descriptions and illustrations of these magnificent Mesozoic beasts. The first section of the book begins with the origin of the great clade of these fascinating reptile ... More This revised edition of this book continues in the same vein as the first but encompasses recent spectacular discoveries that have continued to revolutionize this field. A thorough scientific view of current world research, the volume includes comprehensive coverage of dinosaur systematics, reproduction, and life history strategies, biogeography, taphonomy, paleoecology, thermoregulation, and extinction. It contains definitive descriptions and illustrations of these magnificent Mesozoic beasts. The first section of the book begins with the origin of the great clade of these fascinating reptiles, followed by separate coverage of each major dinosaur taxon, including the Mesozoic radiation of birds. The second part of the volume navigates through broad areas of interest. Here we find comprehensive documentation of dinosaur distribution through time and space, discussion of the interface between geology and biology, and the paleoecological inferences that can be made through this link. This revised edition of this book continues in the same vein as the first but encompasses recent spectacular discoveries that have continued to revolutionize this field. A thorough scientific view of current world research, the volume includes comprehensive coverage of dinosaur systematics, reproduction, and life history strategies, biogeography, taphonomy, paleoecology, thermoregulation, and extinction. It contains definitive descriptions and illustrations of these magnificent Mesozoic beasts. The first section of the book begins with the origin of the great clade of these fascinating reptile ... More