Papers by Femke Holwerda
Peerj, 2018
A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison F... more A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison Formation in Weston County, Wyoming, is described here. Several camarasaurids, a nearly complete small brachiosaur, and a small diplodocid have been found at this locality, but none match the exceptionally large size of the pedal elements. Next to the associated pedal elements, an isolated astragalus, phalanx and ungual were found, which match the large metatarsals in size. The elements cannot be ascribed to diplodocids due to the lack of a ventral process of metatarsal I. Moreover, the morphology of metatarsal V has a broad proximal end, with a long and narrow distal shaft, which differs from Camarasaurus. The size of the material and a medially beveled distal articular surface of metatarsal IV imply an identification as a brachiosaurid. This is the largest pes ever reported from a sauropod dinosaur and represents the first confirmed pedal brachiosaur elements from the Late Jurassic of North America. Furthermore, this brachiosaur material (the pes and the small nearly complete specimen) is the northernmost occurrence of brachiosaurids in the Morrison Formation.
PeerJ, 2019
Four isolated sauropod axial elements from the Oxford Clay Formation (Callovian, Middle Jurassic)... more Four isolated sauropod axial elements from the Oxford Clay Formation (Callovian, Middle Jurassic) of Peterborough, UK, are described. Two associated posterior dorsal vertebrae show a dorsoventrally elongated centrum and short neural arch, and nutrient or pneumatic foramina, most likely belonging to a non-neosauropod eusauropod, but showing ambiguous non-neosauropod eusauropod and neosauropod affinities. An isolated anterior caudal vertebra displays a ventral keel, a ‘shoulder’ indicating a wing-like transverse process, along with a possible prespinal lamina. This, together with an overall high complexity of the anterior caudal transverse process (ACTP) complex, indicates that this caudal could have belonged to a neosauropod. A second isolated middle-posterior caudal vertebra also shows some diagnostic features, despite the neural spine and neural arch not being preserved and the neurocentral sutures being unfused. The positioning of the neurocentral sutures on the anterior one third of the centrum indicates a middle caudal position, and the presence of faint ventrolateral crests, as well as a rhomboid anterior articulation surface, suggest neosauropod affinities. The presence of possible nutrient foramina are only tentative evidence of a neosauropod origin, as they are also found in Late Jurassic non-neosauropod eusauropods. As the caudals from the two other known sauropods from the Peterborough Oxford Clay, Cetiosauriscus stewarti and an indeterminate non-neosauropod eusauropod, do not show the features seen on either of the new elements described, both isolated caudals indicate a higher sauropod species diversity in the faunal assemblage than previously recognised. An exploratory phylogenetic analysis using characters from all four isolated elements supports a basal neosauropod placement for the anterior caudal, and a diplodocid origin for the middle caudal. The dorsal vertebrae are an unstable OTU, and therefore remain part of an indeterminate eusauropod of uncertain affinities. Together with Cetiosauriscus, and other material assigned to different sauropod groups, this study indicates the presence of a higher sauropod biodiversity in the Oxford Clay Formation than previously recognised. This study shows that it is still beneficial to examine isolated elements, as these may be indicators for higher species richness in deposits that are otherwise poor in terrestrial fauna.
Eusauropods were a group of herbivorous dinosaurs that evolved during the Early Jurassic and domi... more Eusauropods were a group of herbivorous dinosaurs that evolved during the Early Jurassic and dominated the terrestrial ecosystems
throughout the Jurassic and Cretaceous. A peak of diversity is represented by the Late Jurassic, when most of the lineages of the derived
clade, Neosauropoda, are represented. Different lineages of eusauropods differ in several morphological aspects, including a great diversity in
gathering strategies, inferred by their dentition morphology and wear facets. Here we describe a new tooth morphotype that can be well
differentiated from any other tooth recovered from the Cañadón Asfalto Formation (Lower–Middle Jurassic). Therefore, this new tooth morphology
increases the evidence of a high diversity of sauropods during that time as well as providing evidence of advanced characters in the
dentition of some Early Jurassic sauropods (e.g., subcylindrical and narrow crowns with single apical wear facet).
Upper Maastrichtian to lower Paleocene, coarse-grained deposits of the Lefip an Formation in Chub... more Upper Maastrichtian to lower Paleocene, coarse-grained deposits of the Lefip an Formation in Chubut Province , (Patagonia, Argentina) provide an opportunity to study environmental changes across the Cretaceous–Palaeo-gene (K–Pg) boundary in a shallow marine depositional environment. Marine palynological and organic geochemical analyses were performed on the K–Pg boundary interval of the Lefip an Formation at the San Ram on section. The paly-nological and organic geochemical records from the San Ram on K–Pg boundary section are characteristic of a highly dynamic, nearshore setting. High abundances of terrestrial palynomorphs, high BIT-index values and the occasional presence of plant fossils are indicative of a large input of terrestrial organic material. The organic-walled dinoflagellate cyst (dinocyst) assemblage is generally dominated by Sene-galinium and other peridinioid dinocyst taxa, indicative of high-nutrient conditions and decreased salinities, probably associated with a large fluvial input. The reconstructed sea surface temperatures range from 25°C to 27°C, in accordance with the tropical climate inferred by palynological and megafloral studies. As in the Bajada del Jag€ uel section, ~500 km north-northeast of San Ram on, peaks of Sene-galinium spp. were recorded below and above the K–Pg boundary, possibly related to enhanced runoff resulting from more humid climatic conditions. The lithological, palynolog-ical and organic geochemical records suggest the occurrence of a sea-level regression across the K–Pg boundary, resulting in a hiatus directly at the boundary in both sections, followed by a transgression in the Danian.
SVP Meeting 2013, Nov 2013
Dinosaur eggs and eggshells of Jurassic age or older are relatively rare worldwide when compared ... more Dinosaur eggs and eggshells of Jurassic age or older are relatively rare worldwide when compared with Cretaceous ones. However, the Lourinha region in central-west Portugal is rich in Kimmeridgian-Tithonian dinosaur egg- and eggshell localities, two
with associated theropod embryo material of Lourinhanosaurus and another large theropod.
Here, we describe specimens from two sites from the Late Kimmeridgian-Early Tithonian Sobral Member of the Lourinha Formation: i) eggshells from Casal da Rola (Museu da Lourinhã [ML]1194) and ii) a new isolated egg from Porto das Barcas
(ML1842). These are compared with previous findings with similar morphology:
Lourinhanosaurus nest from Paimogo (ML565) and clutches from Peralta (ML156), and the theropod clutch ML1403, also from Porto das Barcas but in a different horizon and locality than ML1842. Two main ootaxa were identified: ML1194 as Preprismatoolithus and ML1842 as an undescribed Dendroolithus-like phaceloolithid. The first is clearly identified by the dinosauroid eggshell morphotype angustiprismatic/obliquiprismatic, with an obliquicaniculate or angusticaniculate pore system, smooth outer surface, and an eggshell thickness range of 0.8-1.0 mm. Dendroolithus is identified by: eggs are medium sized (10-20 cm) and spherical in shape; eggshell morphotype dendrospherulitic, with shell
units irregularly shaped and displaying a fanning pattern; pores display a prolatocanaliculate network throughout the eggshell; outer surface ornamentation is irregular with crests and the pores irregularly dispersed between the crests; and average eggshell thickness is approximately 1.1 mm.
The eggshells from Casal da Rola are identical to Preprismatoolithus eggs from Paimogo and Peralta. The eggs from Paimogo have been assigned to Lourinhanosaurus by the presence of embryos, so we ascribe Casal da Rola also to Lourinhanosaurus.
The phaceloolithid egg ML1842 is morphologically identical to the clutch ML1403 found in the same area and assigned to a large theropod. Apart from Porto das Barcas,
Phaceloolithidae is only known from the Late Cretaceous of China and Mongolia.
The early Middle Jurassic is regarded as the period when sauropods diversified and be- came majo... more The early Middle Jurassic is regarded as the period when sauropods diversified and be- came major components of the terrestrial ecosystems. Not many sites yield sauropod mate- rial of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in Central Patagonia (Argentina), which may help to shed light on the early evolution of eusauropods. These eusauropod remains include teeth associated with cranial and man- dibular material as well as isolated teeth found at different localities. In this study, an assem- blage of sauropod teeth from the Cañadón Asfalto Formation found in four different localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based on the shape and orientation of grooves and crests of this wrinkling, we define and describe three different morphotypes. With the exception of one taxon, for which no cranial material is currently known, these morphotypes match the local eusauropod diversity as assessed based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus, whereas morphotypes II and III correspond to new taxa, which are also distinguished by as- sociated postcranial material. This study thus shows that enamel wrinkling can be used as a tool in assessing sauropod diversity.
The early Middle Jurassic is regarded as the period when sauropods diversified and became
major c... more The early Middle Jurassic is regarded as the period when sauropods diversified and became
major components of the terrestrial ecosystems. Not many sites yield sauropod material
of this time; however, both cranial and postcranial material of eusauropods have been
found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in
Central Patagonia (Argentina), which may help to shed light on the early evolution of
eusauropods. These eusauropod remains include teeth associated with cranial and mandibular
material as well as isolated teeth found at different localities. In this study, an assemblage
of sauropod teeth from the Cañadón Asfalto Formation found in four different
localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing
sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based
on the shape and orientation of grooves and crests of this wrinkling, we define and describe
three different morphotypes. With the exception of one taxon, for which no cranial material
is currently known, these morphotypes match the local eusauropod diversity as assessed
based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus,
whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated
postcranial material. This study thus shows that enamel wrinkling can be used as a
tool in assessing sauropod diversity.
OSTEOLOGICAL REVISION OF THE HOLOTYPE OF PATAGOSAURUS
FARIASI, A BASAL EUSAUROPOD FROM ARGENTINA
... more OSTEOLOGICAL REVISION OF THE HOLOTYPE OF PATAGOSAURUS
FARIASI, A BASAL EUSAUROPOD FROM ARGENTINA
HOLWERDA, Femke, Bavarian State collection for Paleontology and Geology/ LMU,
Munich, Germany; RAUHUT, Oliver, Bayerische Staatssammlung fur Palaontologie und
Geologie, Munchen, Germany; POL, Diego, CONICET-MPEF, Trelew, Argentina
The sauropod dinosaur Patagosaurus was found four decades ago in the early Middle
Jurassic Canadon Asfalto Formation, Patagonia, Argentina. It has since been used in
numerous phylogenetic analyses of sauropod dinosaurs. However, our current
understanding of Patagosaurus is based on elements of several specimens collected from
two localities. Furthermore, at least one specimen of one of these localities is probably a
different taxon. Therefore, a revision has been started of all Patagosaurus material,
starting with the holotype, which is described and compared to other sauropods.
The specimen has seven preserved cervical vertebrae, ten dorsals, the complete
sacrum consisting of five sacral vertebrae, and caudals. Furthermore, the right ilium,
pubis and the distal fused parts of the ischia, and the right femur are preserved.
The cervicals are opisthocoelous. Neurocentral sutures are present, indicating that the
animal was still growing. There is a prominant ventral keel, with two lateral fossae
cranially, as in Amygdalodon, Lapparentosaurus and Spinophorosaurus, but in contrast
to Cetiosaurus and derived sauropods. Laterally a shallow pleurocoel is present which is
deeper cranially, as in Spinophorosaurus and Lapparentosaurus, and not as in
Cetiosaurus and Tazoudasaurus. Cranially, the intraprezygapophyseal laminae do not
meet, as in Tazoudasaurus and possibly Cetiosaurus. The anterior and mid-dorsals are
mildly opisthocoelus. The dorsal neural spines are higher than the centrum, and high
neural arches with wider distal dorsal end of the neural spine as in Amygdalodon. A
ventral keel is present in anterior and mid-dorsals but not in posterior dorsals. Laterally
only a small shallow fossa is present, as in Cetiosaurus and Lapparentosaurus. An
infradiapophyseal fenestra below the transverse processes is present as in Barapasaurus
and possibly Tazoudasaurus. The caudals are amphicoelus, as in most basal sauropods.
The ilium is highly arched and craniocaudally elongated. The pubis is twisted towards the
medial plane. The femur is taphonomically deformed. The fourth trochanter is developed
as a non-prominent posteromedial bulge. There is no prominent bulge on the
proximolateral side as in titanosauriforms.
Incorporating the revised scorings of the holotype in an existing matrix,
Patagosaurus fariasi is depicted as the sister taxon of Cetiosaurus forming a clade of
eusauropods more derived than Barapasaurus and Shunosaurus but basal to Omeisaurus
and Mamenchisaurus. This confirms previous ideas on the phylogeny of Patagosaurus.
Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal ... more Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinhã, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.
SVP 2012 annual meeting abstract (poster presentation)
SVP 2011 annual meeting abstract (poster presentation)
Conference Presentations by Femke Holwerda
Sauropods, the emblematic, large, long-necked dinosaurs that are well-represented throughout the ... more Sauropods, the emblematic, large, long-necked dinosaurs that are well-represented throughout the vertebrate fauna of the Mesozoic era, most probably originated from small bipedal/quadrupedal sauropodomorphs. However, their early evolution and origin is not very well understood, and the hypothetical transition from more basal forms to sauropods is particularly poorly studied.
Phylogenetic studies indicate the timing of this transition must have been in the Late Triassic (Norian/Rhaetian), however, ichnofossils from this time indicate that derived sauropodomorphs, or even basal sauropods were already present in the faunal assemblages of Europe.
Well-preserved material of derived sauropodomorphs from this time is known from Argentina, South-Africa, and China, however Europe hosts a wealth of sauropodomorph material as well.
Next to well-known examples as Plateosaurus, Camelotia and Gresslyosaurus, there is material that has not yet received much attention. The Zurich Palaeontological museum holds such material, found at Schleitheim in the kanton of Schaffhausen, Switzerland, which is tentatively dated to be Norian in age. The material had been previously assigned to Gresslyosaurus, but was found to differ from the holotype of this taxon. The material consists of a partial axial skeleton, including two neural arches, a femur, the partial pelvic girdle, and other fragmentary appendicular elements. Moreover, the uniform size and preservation of the material indicate it to be from one individual specimen.
Because it differs morphologically from any other sauropod(omorph) known from this time, it is assigned a new species and genus name; Schleitheimia schutzi, after the locality of Schleitheim and after E. Schutz, the collector of the material.
An extensive phylogenetic analysis combining two recent matrices with additional new characters, retrieves this specimen as a derived sauropodomorph, or even a basal sauropod, depending on which definition of sauropoda is used. It is more derived than Melanorosaurus, Antetonitrus and more basal than Isanosaurus, Pulanesaura and Vulcanodon, placing it within the phylogenetic range of the sauropodomorph-sauropod transition. This not only confirms the presence of more derived sauropodomorphs in the Late Triassic; it also proves a greater diversity of sauropods/sauropodomorphs in the Late Triassic of Europe than previously assumed.
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Papers by Femke Holwerda
throughout the Jurassic and Cretaceous. A peak of diversity is represented by the Late Jurassic, when most of the lineages of the derived
clade, Neosauropoda, are represented. Different lineages of eusauropods differ in several morphological aspects, including a great diversity in
gathering strategies, inferred by their dentition morphology and wear facets. Here we describe a new tooth morphotype that can be well
differentiated from any other tooth recovered from the Cañadón Asfalto Formation (Lower–Middle Jurassic). Therefore, this new tooth morphology
increases the evidence of a high diversity of sauropods during that time as well as providing evidence of advanced characters in the
dentition of some Early Jurassic sauropods (e.g., subcylindrical and narrow crowns with single apical wear facet).
with associated theropod embryo material of Lourinhanosaurus and another large theropod.
Here, we describe specimens from two sites from the Late Kimmeridgian-Early Tithonian Sobral Member of the Lourinha Formation: i) eggshells from Casal da Rola (Museu da Lourinhã [ML]1194) and ii) a new isolated egg from Porto das Barcas
(ML1842). These are compared with previous findings with similar morphology:
Lourinhanosaurus nest from Paimogo (ML565) and clutches from Peralta (ML156), and the theropod clutch ML1403, also from Porto das Barcas but in a different horizon and locality than ML1842. Two main ootaxa were identified: ML1194 as Preprismatoolithus and ML1842 as an undescribed Dendroolithus-like phaceloolithid. The first is clearly identified by the dinosauroid eggshell morphotype angustiprismatic/obliquiprismatic, with an obliquicaniculate or angusticaniculate pore system, smooth outer surface, and an eggshell thickness range of 0.8-1.0 mm. Dendroolithus is identified by: eggs are medium sized (10-20 cm) and spherical in shape; eggshell morphotype dendrospherulitic, with shell
units irregularly shaped and displaying a fanning pattern; pores display a prolatocanaliculate network throughout the eggshell; outer surface ornamentation is irregular with crests and the pores irregularly dispersed between the crests; and average eggshell thickness is approximately 1.1 mm.
The eggshells from Casal da Rola are identical to Preprismatoolithus eggs from Paimogo and Peralta. The eggs from Paimogo have been assigned to Lourinhanosaurus by the presence of embryos, so we ascribe Casal da Rola also to Lourinhanosaurus.
The phaceloolithid egg ML1842 is morphologically identical to the clutch ML1403 found in the same area and assigned to a large theropod. Apart from Porto das Barcas,
Phaceloolithidae is only known from the Late Cretaceous of China and Mongolia.
major components of the terrestrial ecosystems. Not many sites yield sauropod material
of this time; however, both cranial and postcranial material of eusauropods have been
found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in
Central Patagonia (Argentina), which may help to shed light on the early evolution of
eusauropods. These eusauropod remains include teeth associated with cranial and mandibular
material as well as isolated teeth found at different localities. In this study, an assemblage
of sauropod teeth from the Cañadón Asfalto Formation found in four different
localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing
sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based
on the shape and orientation of grooves and crests of this wrinkling, we define and describe
three different morphotypes. With the exception of one taxon, for which no cranial material
is currently known, these morphotypes match the local eusauropod diversity as assessed
based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus,
whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated
postcranial material. This study thus shows that enamel wrinkling can be used as a
tool in assessing sauropod diversity.
FARIASI, A BASAL EUSAUROPOD FROM ARGENTINA
HOLWERDA, Femke, Bavarian State collection for Paleontology and Geology/ LMU,
Munich, Germany; RAUHUT, Oliver, Bayerische Staatssammlung fur Palaontologie und
Geologie, Munchen, Germany; POL, Diego, CONICET-MPEF, Trelew, Argentina
The sauropod dinosaur Patagosaurus was found four decades ago in the early Middle
Jurassic Canadon Asfalto Formation, Patagonia, Argentina. It has since been used in
numerous phylogenetic analyses of sauropod dinosaurs. However, our current
understanding of Patagosaurus is based on elements of several specimens collected from
two localities. Furthermore, at least one specimen of one of these localities is probably a
different taxon. Therefore, a revision has been started of all Patagosaurus material,
starting with the holotype, which is described and compared to other sauropods.
The specimen has seven preserved cervical vertebrae, ten dorsals, the complete
sacrum consisting of five sacral vertebrae, and caudals. Furthermore, the right ilium,
pubis and the distal fused parts of the ischia, and the right femur are preserved.
The cervicals are opisthocoelous. Neurocentral sutures are present, indicating that the
animal was still growing. There is a prominant ventral keel, with two lateral fossae
cranially, as in Amygdalodon, Lapparentosaurus and Spinophorosaurus, but in contrast
to Cetiosaurus and derived sauropods. Laterally a shallow pleurocoel is present which is
deeper cranially, as in Spinophorosaurus and Lapparentosaurus, and not as in
Cetiosaurus and Tazoudasaurus. Cranially, the intraprezygapophyseal laminae do not
meet, as in Tazoudasaurus and possibly Cetiosaurus. The anterior and mid-dorsals are
mildly opisthocoelus. The dorsal neural spines are higher than the centrum, and high
neural arches with wider distal dorsal end of the neural spine as in Amygdalodon. A
ventral keel is present in anterior and mid-dorsals but not in posterior dorsals. Laterally
only a small shallow fossa is present, as in Cetiosaurus and Lapparentosaurus. An
infradiapophyseal fenestra below the transverse processes is present as in Barapasaurus
and possibly Tazoudasaurus. The caudals are amphicoelus, as in most basal sauropods.
The ilium is highly arched and craniocaudally elongated. The pubis is twisted towards the
medial plane. The femur is taphonomically deformed. The fourth trochanter is developed
as a non-prominent posteromedial bulge. There is no prominent bulge on the
proximolateral side as in titanosauriforms.
Incorporating the revised scorings of the holotype in an existing matrix,
Patagosaurus fariasi is depicted as the sister taxon of Cetiosaurus forming a clade of
eusauropods more derived than Barapasaurus and Shunosaurus but basal to Omeisaurus
and Mamenchisaurus. This confirms previous ideas on the phylogeny of Patagosaurus.
Conference Presentations by Femke Holwerda
Phylogenetic studies indicate the timing of this transition must have been in the Late Triassic (Norian/Rhaetian), however, ichnofossils from this time indicate that derived sauropodomorphs, or even basal sauropods were already present in the faunal assemblages of Europe.
Well-preserved material of derived sauropodomorphs from this time is known from Argentina, South-Africa, and China, however Europe hosts a wealth of sauropodomorph material as well.
Next to well-known examples as Plateosaurus, Camelotia and Gresslyosaurus, there is material that has not yet received much attention. The Zurich Palaeontological museum holds such material, found at Schleitheim in the kanton of Schaffhausen, Switzerland, which is tentatively dated to be Norian in age. The material had been previously assigned to Gresslyosaurus, but was found to differ from the holotype of this taxon. The material consists of a partial axial skeleton, including two neural arches, a femur, the partial pelvic girdle, and other fragmentary appendicular elements. Moreover, the uniform size and preservation of the material indicate it to be from one individual specimen.
Because it differs morphologically from any other sauropod(omorph) known from this time, it is assigned a new species and genus name; Schleitheimia schutzi, after the locality of Schleitheim and after E. Schutz, the collector of the material.
An extensive phylogenetic analysis combining two recent matrices with additional new characters, retrieves this specimen as a derived sauropodomorph, or even a basal sauropod, depending on which definition of sauropoda is used. It is more derived than Melanorosaurus, Antetonitrus and more basal than Isanosaurus, Pulanesaura and Vulcanodon, placing it within the phylogenetic range of the sauropodomorph-sauropod transition. This not only confirms the presence of more derived sauropodomorphs in the Late Triassic; it also proves a greater diversity of sauropods/sauropodomorphs in the Late Triassic of Europe than previously assumed.
throughout the Jurassic and Cretaceous. A peak of diversity is represented by the Late Jurassic, when most of the lineages of the derived
clade, Neosauropoda, are represented. Different lineages of eusauropods differ in several morphological aspects, including a great diversity in
gathering strategies, inferred by their dentition morphology and wear facets. Here we describe a new tooth morphotype that can be well
differentiated from any other tooth recovered from the Cañadón Asfalto Formation (Lower–Middle Jurassic). Therefore, this new tooth morphology
increases the evidence of a high diversity of sauropods during that time as well as providing evidence of advanced characters in the
dentition of some Early Jurassic sauropods (e.g., subcylindrical and narrow crowns with single apical wear facet).
with associated theropod embryo material of Lourinhanosaurus and another large theropod.
Here, we describe specimens from two sites from the Late Kimmeridgian-Early Tithonian Sobral Member of the Lourinha Formation: i) eggshells from Casal da Rola (Museu da Lourinhã [ML]1194) and ii) a new isolated egg from Porto das Barcas
(ML1842). These are compared with previous findings with similar morphology:
Lourinhanosaurus nest from Paimogo (ML565) and clutches from Peralta (ML156), and the theropod clutch ML1403, also from Porto das Barcas but in a different horizon and locality than ML1842. Two main ootaxa were identified: ML1194 as Preprismatoolithus and ML1842 as an undescribed Dendroolithus-like phaceloolithid. The first is clearly identified by the dinosauroid eggshell morphotype angustiprismatic/obliquiprismatic, with an obliquicaniculate or angusticaniculate pore system, smooth outer surface, and an eggshell thickness range of 0.8-1.0 mm. Dendroolithus is identified by: eggs are medium sized (10-20 cm) and spherical in shape; eggshell morphotype dendrospherulitic, with shell
units irregularly shaped and displaying a fanning pattern; pores display a prolatocanaliculate network throughout the eggshell; outer surface ornamentation is irregular with crests and the pores irregularly dispersed between the crests; and average eggshell thickness is approximately 1.1 mm.
The eggshells from Casal da Rola are identical to Preprismatoolithus eggs from Paimogo and Peralta. The eggs from Paimogo have been assigned to Lourinhanosaurus by the presence of embryos, so we ascribe Casal da Rola also to Lourinhanosaurus.
The phaceloolithid egg ML1842 is morphologically identical to the clutch ML1403 found in the same area and assigned to a large theropod. Apart from Porto das Barcas,
Phaceloolithidae is only known from the Late Cretaceous of China and Mongolia.
major components of the terrestrial ecosystems. Not many sites yield sauropod material
of this time; however, both cranial and postcranial material of eusauropods have been
found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in
Central Patagonia (Argentina), which may help to shed light on the early evolution of
eusauropods. These eusauropod remains include teeth associated with cranial and mandibular
material as well as isolated teeth found at different localities. In this study, an assemblage
of sauropod teeth from the Cañadón Asfalto Formation found in four different
localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing
sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based
on the shape and orientation of grooves and crests of this wrinkling, we define and describe
three different morphotypes. With the exception of one taxon, for which no cranial material
is currently known, these morphotypes match the local eusauropod diversity as assessed
based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus,
whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated
postcranial material. This study thus shows that enamel wrinkling can be used as a
tool in assessing sauropod diversity.
FARIASI, A BASAL EUSAUROPOD FROM ARGENTINA
HOLWERDA, Femke, Bavarian State collection for Paleontology and Geology/ LMU,
Munich, Germany; RAUHUT, Oliver, Bayerische Staatssammlung fur Palaontologie und
Geologie, Munchen, Germany; POL, Diego, CONICET-MPEF, Trelew, Argentina
The sauropod dinosaur Patagosaurus was found four decades ago in the early Middle
Jurassic Canadon Asfalto Formation, Patagonia, Argentina. It has since been used in
numerous phylogenetic analyses of sauropod dinosaurs. However, our current
understanding of Patagosaurus is based on elements of several specimens collected from
two localities. Furthermore, at least one specimen of one of these localities is probably a
different taxon. Therefore, a revision has been started of all Patagosaurus material,
starting with the holotype, which is described and compared to other sauropods.
The specimen has seven preserved cervical vertebrae, ten dorsals, the complete
sacrum consisting of five sacral vertebrae, and caudals. Furthermore, the right ilium,
pubis and the distal fused parts of the ischia, and the right femur are preserved.
The cervicals are opisthocoelous. Neurocentral sutures are present, indicating that the
animal was still growing. There is a prominant ventral keel, with two lateral fossae
cranially, as in Amygdalodon, Lapparentosaurus and Spinophorosaurus, but in contrast
to Cetiosaurus and derived sauropods. Laterally a shallow pleurocoel is present which is
deeper cranially, as in Spinophorosaurus and Lapparentosaurus, and not as in
Cetiosaurus and Tazoudasaurus. Cranially, the intraprezygapophyseal laminae do not
meet, as in Tazoudasaurus and possibly Cetiosaurus. The anterior and mid-dorsals are
mildly opisthocoelus. The dorsal neural spines are higher than the centrum, and high
neural arches with wider distal dorsal end of the neural spine as in Amygdalodon. A
ventral keel is present in anterior and mid-dorsals but not in posterior dorsals. Laterally
only a small shallow fossa is present, as in Cetiosaurus and Lapparentosaurus. An
infradiapophyseal fenestra below the transverse processes is present as in Barapasaurus
and possibly Tazoudasaurus. The caudals are amphicoelus, as in most basal sauropods.
The ilium is highly arched and craniocaudally elongated. The pubis is twisted towards the
medial plane. The femur is taphonomically deformed. The fourth trochanter is developed
as a non-prominent posteromedial bulge. There is no prominent bulge on the
proximolateral side as in titanosauriforms.
Incorporating the revised scorings of the holotype in an existing matrix,
Patagosaurus fariasi is depicted as the sister taxon of Cetiosaurus forming a clade of
eusauropods more derived than Barapasaurus and Shunosaurus but basal to Omeisaurus
and Mamenchisaurus. This confirms previous ideas on the phylogeny of Patagosaurus.
Phylogenetic studies indicate the timing of this transition must have been in the Late Triassic (Norian/Rhaetian), however, ichnofossils from this time indicate that derived sauropodomorphs, or even basal sauropods were already present in the faunal assemblages of Europe.
Well-preserved material of derived sauropodomorphs from this time is known from Argentina, South-Africa, and China, however Europe hosts a wealth of sauropodomorph material as well.
Next to well-known examples as Plateosaurus, Camelotia and Gresslyosaurus, there is material that has not yet received much attention. The Zurich Palaeontological museum holds such material, found at Schleitheim in the kanton of Schaffhausen, Switzerland, which is tentatively dated to be Norian in age. The material had been previously assigned to Gresslyosaurus, but was found to differ from the holotype of this taxon. The material consists of a partial axial skeleton, including two neural arches, a femur, the partial pelvic girdle, and other fragmentary appendicular elements. Moreover, the uniform size and preservation of the material indicate it to be from one individual specimen.
Because it differs morphologically from any other sauropod(omorph) known from this time, it is assigned a new species and genus name; Schleitheimia schutzi, after the locality of Schleitheim and after E. Schutz, the collector of the material.
An extensive phylogenetic analysis combining two recent matrices with additional new characters, retrieves this specimen as a derived sauropodomorph, or even a basal sauropod, depending on which definition of sauropoda is used. It is more derived than Melanorosaurus, Antetonitrus and more basal than Isanosaurus, Pulanesaura and Vulcanodon, placing it within the phylogenetic range of the sauropodomorph-sauropod transition. This not only confirms the presence of more derived sauropodomorphs in the Late Triassic; it also proves a greater diversity of sauropods/sauropodomorphs in the Late Triassic of Europe than previously assumed.