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The genus name Syntarsus Raath 1969 is preoccupied by the genus Syntarsus Fairmaire 1869. The replacement name Megapnosaurus Ivie et al. 2001 was proposed but its usage is inconsistent due to both controversy on the validity of the nomenclatural act proposing Megapnosaurus and possible synonymy between it and Coelophysis Cope 1889. The nomenclatural act proposing Megapnosaurus is found to be valid, while synonymy between the genera Megapnosaurus and Coelophysis is considered uncertain. Therefore, the names Megapnosaurus rhodesiensis and Coelophysis rhodesiensis are both considered possibly correct names for the type species of Syntarsus Raath 1969, though here the name Megapnosaurus rhodesiensis is preferred.
The Mosasaur
Volume 12, July 2022
The Journal of the Delaware Valley Paleontological Society
David C. Parris
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ABSTRACT - The genus name Syntarsus Raath 1969 is preoccupied by the genus Syntarsus
Fairmaire 1869. The replacement name Megapnosaurus Ivie et al. 2001 was proposed but its usage
is inconsistent due to both controversy on the validity of the nomenclatural act proposing
Megapnosaurus and possible synonymy between it and Coelophysis Cope 1889. The nomenclatural
act proposing Megapnosaurus is found to be valid, while synonymy between the genera
Megapnosaurus and Coelophysis is considered uncertain. Therefore, the names Megapnosaurus
rhodesiensis and Coelophysis rhodesiensis are both considered possibly correct names for the type
species of Syntarsus Raath 1969, though here the name Megapnosaurus rhodesiensis is preferred.
Keywords: Megapnosaurus, Coelophysis, Theropoda, Taxonomy
The theropod dinosaur genus Syntarsus Raath 1969,
with type species Syntarsus rhodesiensis Raath
1969, was named based on fossils from
Nyamandhlovu, Zimbabwe (then Rhodesia). (Raath,
1969) Its generic name is preoccupied by the genus
Syntarsus Fairmaire 1869, a modern beetle from
Madagascar. (Ivie et al., 2001) In accordance with
the International Code of Zoological Nomenclature,
Ivie et al. (2001) proposed the replacement name
Megapnosaurus. Most recent authors (e.g., Griffin
and Nesbitt, 2016; Barta et al., 2018; Griffin, 2018;
Ezcurra et al., 2021; Brody, 2021, Spiekman et al.,
2021) have followed this and used the name
Megapnosaurus rhodesiensis to refer to the species
originally described as Syntarsus rhodesiensis.
However, this has not been followed universally.
The genus Syntarsus Raath 1969 has been
considered by some authors to be synonymous with
the genus Coelophysis Cope 1889. (Paul, 1993;
Bristowe and Raath, 2004; Yates, 2005; Paul, 2016).
Some authors have continued to refer to the
dinosaur genus as Syntarsus despite a replacement
name being proposed. (Bristowe and Raath, 2004;
Tyloski and Rowe, 2004.) Additionally, Ezcurra
(2007) considers rhodesiensis a species of
Coelophysis but treats Syntarsus as a valid genus
containing the species Syntarsus kayentakatae
Rowe 1989, which was originally described as a
second species of Syntarsus Raath. (Rowe, 1989)
Ezcurra and Brusatte (2011) follow Ezcurra (2007) in
their usage of Coelophysis rhodesiensis, though they
refer to the species originally described as Syntarsus
kayentakatae as Syntarsus kayentakatae, with
quotation marks in recognition of the preoccupied
status of Syntarsus, despite the replacement name
Megapnosaurus having been proposed.
AMNH - American Museum of Natural History, New
York, United States
BP - Bernard Price Institute for Palaeontological
Research (University of the Witwatersrand),
Johannesburg, South Africa
CMNH - Cleveland Museum of Natural History,
Cleveland, United States
NHMUK - Natural History Museum, London, United
QG - Zimbabwe Natural History Museum, Bulawayo,
The genus Syntarsus Fairmaire 1869 is a modern
beetle (Insecta: Coleoptera) from Madagascar.
(Marie and Lesne, 1940) According to Ivie and
Ślipiński (1990), the genus is a junior synonym of
Cerchanotus Erichson 1845. The publication
proposing the name is found to fulfill the
requirements of the International Code of
Zoological Nomenclature. Furthermore, multiple
later sources refer to it (e.g., Marie and Lesne,
1940; Ślipiński, 1985, Ivie and Ślipiński 1990; Ivie
et al., 2001) and none question the validity of the
nomenclatural act. Therefore, it is here
considered to have been validly named. Even
though it is a junior synonym of Cerchanotus, the
name Syntarsus remains unavailable for a new
genus per the Code. (Ivie et al., 2001; ICZN 1999)
TAXONOMIC VALIDITY OF Megapnosaurus Ivie et
al., 2001
Megapnosaurus was proposed as a replacement for
the preoccupied Syntarsus Raath 1969 by Ivie et al.,
(2001). The publication proposing this name fulfills
all requirements of the International Code of
Zoological Nomenclature for a replacement name.
It is therefore considered to have been validly
named, despite a possible synonymy with
Coelophysis discussed later.
If a taxonomic name is invalid (preoccupied or
incorrectly formulated), then it is considered ethical
to contact its original describer or describers to
inform them of the problem so that they can correct
their own error. If the original describer or
describers are unreachable (for example if they are
deceased or do not respond to correspondence)
then the person who learns of the error will typically
publish a correction. Ivie attempted to contact
Raath but never received a reply. He and coauthors
proceeded with publication of the replacement
name after two years, and after being (incorrectly)
told by dinosaur paleontologist John “Jack” Horner
that Raath was deceased. (Michael Ivie, pers.
The naming of Megapnosaurus was described as
“facetious” by Bristowe and Raath (2004), likely due
to it having a humorous etymology.
Megapnosaurus is derived from Ancient Greek and
translated by Ivie et al. (2001) as “big dead lizard,”
though perhaps a more accurate translation would
be “big lizard without breath.” They say they chose
this name because “to the scale of an entomologist,
[Megapnosaurus] looks like a big dead lizard.”
Although humorous etymologies are uncommon in
vertebrate paleontology, they are common in
entomology. The entomologists who named
Megapnosaurus were acting in a manner that is
standard in their field, and compliant with the Code
of Ethics of Zoological Nomenclature, which
requires waiting one year before considering the
original describer unreachable. (Appendix A of ICZN,
Regardless of the ethics surrounding the naming of
Megapnosaurus, the publication naming it is
taxonomically valid, and it remains the correct
name for the dinosaur originally described as
Syntarsus Raath 1969 if it is not considered a
member of the genus Coelophysis.
SYNONYMY OF Megapnosaurus AND Coelophysis
The genus Megapnosaurus was validly named as a
replacement for the preoccupied name Syntarsus,
and therefore is the correct name for the dinosaur
genus if there is no older synonym. (ICZN, 1999)
There are no older names that are definitively
synonymous with Megapnosaurus, though there is
one possible senior synonym: Coelophysis. In fact,
Paul (1993) suggested that Coelophysis bauri was a
possible nomen dubium and suggested the use of
Syntarsus colberti for the Ghost Ranch theropods. A
diagnostic neotype (AMNH 7224) was later selected
from among the Ghost Ranch specimens to replace
the possibly non-diagnostic lectotype of
Coelophysis bauri, making Coelophysis bauri the
correct name for the Ghost Ranch theropods. (ICZN,
Bristowe and Raath (2004) argued that Coelophysis
and Megapnosaurus were synonymous and treated
the name Megapnosaurus as invalid, instead using
the name ‘Syntarsus rhodesiensis with the genus in
quotation marks to indicate that the species
rhodesiensis could not be assigned to the
preoccupied genus Syntarsus. In this same paper,
they described a juvenile skull (QG165) which they
referred to Coelophysis rhodesiensis. This skull is
similar to CMNH 50957, a juvenile Coelophysis bauri
skull from Ghost Ranch, which will be described by
us in detail in a later publication.
On the other hand, phylogenetic analysis by Ezcurra
et al. (2021) found that the genus Coelophysis
would be polyphyletic if it included both bauri and
rhodesiensis, supporting the separation of the
genera Megapnosaurus and Coelophysis. Another
analysis by Martínez and Apaldetti (2017) found
that Coelophysis bauri was the sister taxon to the
clade containing Coelophysis rhodesiensis,
Camposaurus Hunt et al. 1998, and Lucianovenator
Martínez and Apaldetti 2017, with the relationships
between the latter three being uncertain, making
the genus Coelophysis either paraphyletic or
polyphyletic if rhodesiensis is included. Barta et al.
(2018) also noted anatomical differences between
the two species. They treated Megapnosaurus as a
separate genus from Coelophysis, but the
differences they described could be argued to
represent differences between congeneric species.
The genus Megapnosaurus is here considered to be
likely distinct from Coelophysis, but in need of
further research.
Raath 1969
Rauhut and Hungerbühler (1998) referred a
theropod specimen from Wales, UK to Syntarsus sp.
This specimen (NHMUK PV R 37591) was later
determined by Spiekman et al. (2021) to be a non-
Coelophysid Coelophysoid and placed in the new
genus and species Pendraig milnerae Spiekman et
al. 2021. This interpretation is followed here, and
Pendraig is considered valid and distinct from
Coelophysis and Megapnosaurus.
Munyikwa and Raath (1999) described a snout tip
(BP/1/5278) which they referred to Syntarsus
rhodesiensis from the Early Jurassic Elliot Formation
of South Africa. This specimen was reassessed by
Yates (2005) who tentatively referred it to
Dracovenator regenti Yates 2005. Here we follow
Yates’ (2005) tentative referral but want to
emphasize that this referral is tentative.
Syntarsus kayentakatae was named as a second
species of the genus Syntarsus Raath 1969, not as a
species of the genus Syntarsus Fairmaire 1869.
(Rowe, 1989) Syntarsus Raath 1969, if not
synonymous with Coelophysis, is properly called
Megapnosaurus, so the species Syntarsus
kayentakatae would normally be transferred to the
genus Megapnosaurus as Megapnosaurus
kayentakatae. Indeed, this combination is proposed
by Ivie et al., (2001) and used by some subsequent
authors (e.g., Senter and Robins, 2015). However,
multiple phylogenetic analyses found that the
placement of kayentakatae in either
Megapnosaurus or its possible synonym
Coelophysis would render its genus polyphyletic.
(Martínez and Apaldetti, 2017; Ezcurra et al, 2021)
It therefore cannot be considered part of the genera
Megapnosaurus or Coelophysis, most likely
representing its own genus. It is thus recommended
that this species provisionally be referred to as
Megapnosaurus kayentakatae, with quotation
marks indicating a problematic genus assignment,
until a new genus is formally described for this
The species originally described as Syntarsus
rhodesiensis cannot correctly be called Syntarsus
rhodesiensis. The proper replacement name is
Megapnosaurus rhodesiensis. Megapnosaurus is
possibly a junior synonym of Coelophysis, but until
this is firmly proven or disproven, the placement of
the species in either the genus Megapnosaurus or
Coelophysis is considered acceptable. Usage of the
name Megapnosaurus rhodesiensis is
recommended. Usage of the name Coelophysis
rhodesiensis is neither recommended nor
discouraged. Usage of the name Syntarsus
rhodesiensis is discouraged. The species originally
described as Syntarsus kayentakate most likely
represents a different genus from Megapnosaurus
rhodesiensis, but until this genus is formally named,
the provisional name Megapnosaurus
kayentakatae is recommended.
The authors wish to thank Tyler Greenfield for
help finding nineteenth-century literature.
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6 THE MOSASAUR – Vol. 12
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We describe a new small-bodied coelophysoid theropod dinosaur, Pendraig milnerae gen. et sp. nov, from the Late Triassic fissure fill deposits of Pant-y-ffynnon in southern Wales. The species is represented by the holotype, consisting of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium. Our phylogenetic analysis recovers P. milnerae as a non-coelophysid coelophysoid theropod, representing the first-named unambiguous theropod from the Triassic of the UK. Recently, it has been suggested that Pant-y-ffynnon and other nearby Late Triassic to Early Jurassic fissure fill faunas might have been subjected to insular dwarfism. To test this hypothesis for P. milnerae , we performed an ancestral state reconstruction analysis of body size in early neotheropods. Although our results indicate that a reduced body size is autapomorphic for P. milnerae , some other coelophysoid taxa show a similar size reduction, and there is, therefore, ambiguous evidence to indicate that this species was subjected to dwarfism. Our analyses further indicate that, in contrast with averostran-line neotheropods, which increased in body size during the Triassic, coelophysoids underwent a small body size decrease early in their evolution.
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The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ among reconstructions and among skeletal mounts. For most dinosaurian taxa, no attempt has previously been made to quantify the correct resting positions of these elements. Here, we used data from skeletons preserved in articulation to quantify the resting orientations of the scapula and forelimb in dinosaurs. Specimens were included in the study only if they were preserved lying on their sides; for each specimen the angle between forelimb bones at a given joint was included in the analysis only if the joint was preserved in articulation. Using correlation analyses of the angles between the long axis of the sacrum, the first dorsal centrum, and the scapular blade in theropods and Eoraptor, we found that vertebral hyperextension does not influence scapular orientation in saurischians. Among examined taxa, the long axis of the scapular blade was found to be most horizontal in bipedal saurischians, most vertical in basal ornithopods, and intermediate in hadrosauroids. We found that in bipedal dinosaurs other than theropods with semilunate carpals, the resting orientation of the elbow is close to a right angle and the resting orientation of the wrist is such that the hand exhibits only slight ulnar deviation from the antebrachium. In theropods with semilunate carpals the elbow and wrist are more flexed at rest, with the elbow at a strongly acute angle and with the wrist approximately at a right angle. The results of our study have important implications for correct orientations of bones in reconstructions and skeletal mounts. Here, we provide recommendations on bone orientations based on our results.
Neotheropoda represents the main evolutionary radiation of predatory dinosaurs and its oldest records come from Upper Triassic rocks (c. 219 Mya). The Early Jurassic record of Neotheropoda is taxonomically richer and geographically more widespread than that of the Late Triassic. The Lower Jurassic (upper Hettangian–lower Sinemurian) rocks of central England have yielded three neotheropod specimens that have been assigned to two species within the genus Sarcosaurus, S. woodi (type species) and S. andrewsi. These species have received little attention in discussions of the early evolution of Neotheropoda and recently have been considered as nomina dubia. Here, we provide a detailed redescription of one of these specimens (WARMS G667–690) and reassess the taxonomy and phylogenetic relationships of the genus Sarcosaurus. We propose that the three neotheropod specimens from the Early Jurassic of central England represent a single valid species, S. woodi. The second species of the genus, ‘S. andrewsi’, is a subjective junior synonym of the former. A quantitative phylogenetic analysis of early theropods recovered S. woodi as one of the closest sister-taxa to Averostra and provides new information on the sequence of character state transformations in the lead up to the phylogenetic split between Ceratosauria and Tetanurae.
Two further fossils recovered from the Elliot Formation in South Africa are referred to the ceratosaurian genus Syntarsus: a partial pelvis and a well preserved and articulated snout. The pelvic fragment consists of most of the posterior end of the left ilium and sacrum, with a small part of the right ilium attached. The acetabular area and 'brevis shelf' of the left ilium are well preserved, as is the ventral surface of the sacrum. These parts show features characteristic of Syntarsus material from Zimbabwe. The snout has the premaxillae, maxillae, nasals and dentaries from both sides preserved, of which only the premaxillae are more or less complete. The premaxilla has four alveoli and the maxilla nine, and the maxilla bears the characteristic dimpling on its lateral surface also seen in Syntarsus material collected in Zimbabwe. The snout also possesses the characteristic small diastema or subnarial gap between the premaxillary and maxillary teeth shown by Syntarsus material from elsewhere. The snout is strongly compressed bilaterally and the jaws are tightly closed, so that the dentary teeth are obscured beneath the upper dentition. This compression has crushed the palatal region, obscuring palatal details.
Several authors have drawn attention to the close similarities between the neotheropod dinosaurs Coelophyis and Syntarsus. Reconstruction and analysis of a skull from a juvenile specimen of Syntarsus (collected from the Forest Sandstone Formation of Zimbabwe) show that cranial characters previously used to distinguish these taxa and justify their generic separation (namely the presence of a 'nasal fenestra' in Syntarsus and the length of its antorbital fenestra), were based on erroneous reconstructions of disassociated cranial elements. On the basis of this reinterpretation we conclude that Syntarsus is a junior synonym of Coelophysis. Variations are noted in three cranial characters - the length of the maxillary tooth row, the width of the base of the lachrymal and the shape of the antorbital maxillary fossa - that taken together with the chronological and geographical separation of the two taxa justify separation at species level.