The systematic position of the Late Jurassic alleged dinosaur Macelognathus (Crocodylomorpha: Sphenosuchia)

2005 ◽  
Vol 42 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Ursula B Göhlich ◽  
Luis M Chiappe ◽  
James M Clark ◽  
Hans-Dieter Sues
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Systematic Position ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Morrison Formation ◽  
Postcranial Skeleton ◽  
Western Colorado ◽  
New Material ◽  
Limb Posture

Macelognathus vagans was described by O.C. Marsh in 1884, based on a mandibular symphysis from the Upper Jurassic Morrison Formation of Wyoming. Often considered a dinosaur but later tentatively referred to the Crocodylia, its phylogenetic identity has until now been enigmatic. New material of this species from the Morrison Formation of western Colorado demonstrates its affinities with basal crocodylomorphs commonly grouped together as the Sphenosuchia, which are characterized by a gracile postcranial skeleton with erect limb posture. Macelognathus shares features with Kayentasuchus from the Lower Jurassic Kayenta Formation of Arizona and Hallopus, which may be from the Morrison Formation of eastern Colorado. The new material constitutes the youngest definitive occurrence of a sphenosuchian, previously known from the Late Triassic to the Middle or Late? Jurassic.

scholarly journals Decomposition of dinosaurian remains inferred by invertebrate traces on vertebrate bone reveal new insights into Late Jurassic ecology, decay, and climate in western Colorado

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9510
Author(s):  
Julia B. McHugh ◽  
Stephanie K. Drumheller ◽  
Anja Riedel ◽  
Miriam Kane
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Site Formation ◽  
Morrison Formation ◽  
Bone Surface ◽  
The North ◽  
Western Colorado ◽  
Burial Rates ◽  
Minimum Residence Time ◽  
Taphonomic Analysis

A survey of 2,368 vertebrate fossils from the Upper Jurassic Mygatt-Moore Quarry (MMQ) (Morrison Formation, Brushy Basin Member) in western Colorado revealed 2,161 bone surface modifications on 884 specimens. This is the largest, site-wide bone surface modification survey of any Jurassic locality. Traces made by invertebrate actors were common in the assemblage, second in observed frequency after vertebrate bite marks. Invertebrate traces are found on 16.174% of the total surveyed material and comprise 20.148% of all identified traces. Six distinct invertebrate trace types were identified, including pits and furrows, rosettes, two types of bioglyph scrapes, bore holes and chambers. A minimum of four trace makers are indicated by the types, sizes and morphologies of the traces. Potential trace makers are inferred to be dermestid or clerid beetles, gastropods, an unknown necrophagous insect, and an unknown osteophagus insect. Of these, only gastropods are preserved at the site as body fossils. The remaining potential trace makers are part of the hidden paleodiversity from the North American Late Jurassic Period, revealed only through this ichnologic and taphonomic analysis. Site taphonomy suggests variable, but generally slow burial rates that range from months up to 6 years, while invertebrate traces on exposed elements indicate a minimum residence time of five months for carcasses with even few preserved invertebrate traces. These traces provide insight into the paleoecology, paleoclimate, and site formation of the MMQ, especially with regards to residence times of the skeletal remains on the paleolandscape. Comprehensive taphonomic studies, like this survey, are useful in exploring patterns of paleoecology and site formation, but they are also rare in Mesozoic assemblages. Additional work is required to determine if 16.174% is typical of bulk-collected fossils from Jurassic ecosystems in North America, or if the MMQ represents an unusual locality.

scholarly journals Detrital zircon geochronology and provenance of the Middle to Late Jurassic Paradox Basin and Central Colorado trough: Paleogeographic implications for southwestern Laurentia

Geosphere ◽  
2021 ◽  
Author(s):  
John I. Ejembi ◽  
Sally L. Potter-McIntyre ◽  
Glenn R. Sharman ◽  
Tyson M. Smith ◽  
Joel E. Saylor ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Detrital Zircon ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Morrison Formation ◽  
Detrital Zircon Geochronology ◽  
Sediment Dispersal ◽  
Paradox Basin ◽  
Southern Oklahoma ◽  
Trace Elemental

Middle to Upper Jurassic strata in the Paradox Basin and Central Colorado trough (CCT; south­western United States) record a pronounced change in sediment dispersal from dominantly aeolian deposition with an Appalachian source (Entrada Sandstone) to dominantly fluvial deposi­tion with a source in the Mogollon and/or Sevier orogenic highlands (Salt Wash Member of the Morrison Formation). An enigmatic abundance of Cambrian (ca. 527–519 Ma) grains at this prove­nance transition in the CCT at Escalante Canyon, Colorado, was recently suggested to reflect a local sediment source from the Ancestral Front Range, despite previous interpretations that local base­ment uplifts were largely buried by Middle to Late Jurassic time. This study aims to delineate spatial and tem­poral patterns in provenance of these Jurassic sandstones containing Cambrian grains within the Paradox Basin and CCT using sandstone petrog­raphy, detrital zircon U-Pb geochronology, and detrital zircon trace elemental and rare-earth ele­mental (REE) geochemistry. We report 7887 new U-Pb detrital zircon analyses from 31 sandstone samples collected within seven transects in west­ern Colorado and eastern Utah. Three clusters of zircon ages are consistently present (1.53–1.3 Ga, 1.3–0.9 Ga, and 500–300 Ma) that are interpreted to reflect sources associated with the Appalachian orogen in southeastern Laurentia (mid-continent, Grenville, Appalachian, and peri-Gondwanan terranes). Ca. 540–500 Ma zircon grains are anom­alously abundant locally in the uppermost Entrada Sandstone and Wanakah Formation but are either lacking or present in small fractions in the overlying Salt Wash and Tidwell Members of the Morrison Formation. A comparison of zircon REE geochem­istry between Cambrian detrital zircon and igneous zircon from potential sources shows that these 540–500 Ma detrital zircon are primarily magmatic. Although variability in both detrital and igneous REE concentrations precludes definitive identifica­tion of provenance, several considerations suggest that distal sources from the Cambrian granitic and rhyolitic provinces of the Southern Oklahoma aulacogen is also likely, in addition to a proximal source identified in the McClure Mountain syenite of the Wet Mountains, Colorado. The abundance of Cambrian grains in samples from the central CCT, particularly in the Entrada Sandstone and Wana­kah Formation, suggests northwesterly sediment transport within the CCT, with sediment sourced from Ancestral Rocky Mountains uplifts of the southern Wet Mountains and/or Amarillo-Wichita Mountains in southwestern Oklahoma. The lack of Cambrian grains within the Paradox Basin sug­gests that the Uncompahgre uplift (southwestern Colorado) acted as a barrier to sediment transport from the CCT.

scholarly journals Assemblage-level structure in Morrison Formation dinosaurs, Western Interior, USA

2018 ◽  
Vol 5 ◽  
pp. 9-22 ◽  
Author(s):  
John Whitlock ◽  
Kelli Trujillo ◽  
Gina Hanik
Keyword(s):  
South Dakota ◽  
Level Structure ◽  
Upper Jurassic ◽  
Bipartite Network ◽  
Morrison Formation ◽  
Depositional History ◽  
East Central ◽  
Alpha And Beta Diversity ◽  
Western Colorado ◽  
Genus Richness

­The Upper Jurassic Morrison Formation is both geographically extensive and well-sampled, making it an ideal candidate for biogeographic analysis at both coarse and finer scales. Historically, however, this has not translated into a consensus on patterns of ecological structure and connectivity, particularly with regard to the characteristic dinosaur faunas. Here, we use both traditional (genus richness, alpha and beta diversity) and bipartite network-based (biogeographic connectivity, local endemism, and average occurrence) measures to examine patterns of structure on a per-locality basis. Given the broad geographic range of the formation, we subdivide the Morrison Formation into four discrete regions based roughly on latitude and lithology—north (Montana, South Dakota, and northern Wyoming), west (Utah and western Colorado), east (central and eastern Colorado and southern Wyoming), and south (Arizona, New Mexico and Oklahoma). Further investigation revealed many coeval sites (ca. 152 Ma) in the east and west regions. Presence-absence data were also compared using network analysis to determine the presence and content of discrete subassemblages within the larger region-level assemblages. Based on our results, we favor reconstructions of the Morrison Formation as a ‘mosaic’ type environment over most of its depositional history, with patches of open environments interspersed with more closed, forested regions. ­is is suggested by relatively low rates of local endemism (patches are consistent in plant and animal structure) and connectivity across the majority of the formation, as well as the recovery of three non-overlapping assemblages dominated by dierent guilds of herbivorous dinosaurs.

scholarly journals A new, nearly complete stem turtle from the Jurassic of South America with implications for turtle evolution

2008 ◽  
Vol 4 (3) ◽  
pp. 286-289 ◽  
Author(s):  
Juliana Sterli
Keyword(s):  
South America ◽  
Late Jurassic ◽  
Cladistic Analysis ◽  
Upper Jurassic ◽  
Upper Triassic ◽  
Late Triassic ◽  
Closure Mechanism

Turtles have been known since the Upper Triassic (210 Myr old); however, fossils recording the first steps of turtle evolution are scarce and often fragmentary. As a consequence, one of the main questions is whether living turtles (Testudines) originated during the Late Triassic (210 Myr old) or during the Middle to Late Jurassic ( ca 160 Myr old). The discovery of the new fossil turtle, Condorchelys antiqua gen. et sp. nov., from the Middle to Upper Jurassic ( ca 160–146 Myr old) of South America (Patagonia, Argentina), presented here sheds new light on early turtle evolution. An updated cladistic analysis of turtles shows that C. antiqua and other fossil turtles are not crown turtles, but stem turtles. This cladistic analysis also shows that stem turtles were more diverse than previously thought, and that until the Middle to Upper Jurassic there were turtles without the modern jaw closure mechanism.

Proapocritus lini sp. nov., a new ephialtitid wasp (Hymenoptera: Apocrita) from the Middle-Upper Jurassic of Daohugou, NE China

2020 ◽  
Vol 3 (1) ◽  
pp. 054-058
Author(s):  
HAICHUN ZHANG
Keyword(s):  
Lower Cretaceous ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Lower Jurassic ◽  
Ne China ◽  
Basal Group

The Ephialtitidae is an extinct family of wasps, with 29 genera reported from the Lower Jurassic-Lower Cretaceous in Kyrgyzstan, Kazakhstan, China, Mongolia, Russia, Spain, Germany and Brazil, and flourished in the Middle–Late Jurassic (Meunier, 1903; Rasnitsyn, 1975, 1977, 1990, 1999, 2008a, b; Zessin, 1981, 1985; Zhang, 1986; Darling & Sharkey, 1990; Rasnitsyn & Ansorge, 2000; Rasnitsyn & Martínez-Delclòs, 2000; Zhang et al., 2002; Rasnitsyn et al., 2003; Rasnitsyn & Zhang, 2004, 2010; Zhang et al., 2010; Ding et al., 2013, 2016; Li et al., 2013, 2014, 2015; Zhang et al., 2014). It is considered to be the most basal group of the Apocrita, one of two suborders of the order Hymenoptera (Rasnitsyn & Zhang, 2010).

scholarly journals Selachians and actinopterygians from the Upper Jurassic of Tendaguru, Tanzania

Fossil Record ◽  
2002 ◽  
Vol 5 (1) ◽  
pp. 207-230 ◽  
Author(s):  
G. Arratia ◽  
J. Kriwet ◽  
W.-D. Heinrich
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Actinopterygian Fishes ◽  
New Material

Abstract. The first Late Jurassic selachian and actinopterygian fishes of Tendaguru in Tanzania were collected by the German-Tendaguru expedition in 1909–1913. They are represented mainly by occasional teeth of a neoselachian (Sphenodus) and several specimens of a neopterygian (Lepidotes). New material collected by the German-Tanzanian Tendaguru expedition in 2000 includes additional selachians recovered from clay stones at site Dwa 5a and isolated actinopterygian remains. At least three hybodonts (Hybodus sp., Hybodontidae indet., Lonchidion sp.) and a new neoselachian batoid are presented here. This assemblage is endemic to Tendaguru. A new batoid genus and species, Engaibatis schultzei, is described, which is the oldest record of a ray from Gondwana. The actinopterygians are represented by scarce and disarticulated scales of Lepidotes, "pholidophoriform"-like scales, and teleostean vertebrae. This material includes new biogeographic records for Africa. In addition, a synopsis of Jurassic fishes from Africa is presented. Die Fischfauna aus dem Oberjura von Tendaguru ist bisher nur unzureichend bekannt. Das erste Material, das von der Deutschen Tendaguru-Expedition (1909–1913) gesammelt wurde, besteht fast nur aus einigen wenigen isolierten Zähne des Haies Sphenodus und mehreren Exemplaren des Actinopterygiers Lepidotes. Neue Funde, die während der Deutsch-Tansanischen-Tendaguru-Expedition im Jahre 2000 geborgen wurden, erlauben es, mehrere Taxa zu beschreiben, die aus dem Oberjura Afrikas noch nicht bekannt waren. Anhand von Zähnen konnten mindestens drei zu den ursprünglichen Hybodontiern zählende Taxa (Hybodus sp., Hybodontidae indet., Lonchidion sp.) nachgewiesen sowie ein für Tendaguru neuer Rochen (Engaibatis schultzei n. gen. and n. sp.) festgestellt werden. Actinopterygier sind durch wenige und disartikulierte Schuppen von Lepidotes und einer "pholidophoriden"-ähnlichen Form sowie durch Wirbel von Teleosteern vertreten. Das neue Material gibt wichtige Hinweise auf die paläobiogeographische Verbreitung der spätjurassischen Fische. Es wird ein Überblick über die bisher bekannten jurassischen Fischfaunen Afrikas gegeben. doi:10.1002/mmng.20020050112x

scholarly journals An unusually diverse northern biota from the Morrison Formation (Upper Jurassic), Black Hills, Wyoming

2020 ◽  
Vol 7 ◽  
pp. 29-67
Author(s):  
John Foster ◽  
Darrin Pagnac ◽  
ReBecca Hunt-Foster
Keyword(s):  
North America ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
River Channel ◽  
Black Hills ◽  
Morrison Formation ◽  
Vertebrate Fauna ◽  
Type Area ◽  
First Occurrence

The Little Houston Quarry in the Black Hills of Wyoming contains the most diverse vertebrate fauna in the Morrison Formation (Upper Jurassic) north of Como Bluff and the second-most diverse in the entire formation, after Reed’s Quarry 9. The deposit was an occasionally reactivated abandoned river channel, in interbedded green mudstone and laminated green-gray siltstone above a channel sandstone. The dinosaur material is densely distributed and is disarticulated to articulated, with several associated skeletons. The biota contains charophytes, horsetails, a possible seed fern, possible conifers, gastropods, two types of unionoid bivalves, diplostracans (“conchostracans”), a malacostracan, ray-finned fish, lungfish, a frog, salamanders, two types of turtles, rhynchocephalians, a lizard, choristoderes, two types of crocodyliforms, a pterosaur, Allosaurus and several types of small theropods including Tanycolagreus? and probable dromaeosaurids, numerous Camarasaurus and a diplodocine sauropod, a stegosaur, the neornithischian Nanosaurus, and the mammals Docodon, Amblotherium, and a multituberculate. Among these taxa, one of the unionoid bivalves, an atoposaurid crocodyliform, and the species of Amblotherium, which appear to be new and unique to the locality so far. The Docodon material may represent the first occurrence of D. apoxys outside of its type area in Colorado. Additionally, small, unusual theropod tooth types reported here may represent the first Late Jurassic occurrence of cf. Richardoestesia in North America and a possible abelisauroid, respectively.

scholarly journals Paleontology, taphonomy, and sedimentology of the Mygatt-Moore Quarry, a large dinosaur bonebed in the Morrison Formation, western Colorado—Implications for Upper Jurassic dinosaur preservation modes

2018 ◽  
Vol 5 ◽  
pp. 23-93 ◽  
Author(s):  
John Foster ◽  
ReBecca Hunt-Foster ◽  
Mark Gorman ◽  
Kelli Trujillo ◽  
Celina Suarez ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Plant Material ◽  
Upper Jurassic ◽  
Morrison Formation ◽  
Close Inspection ◽  
Fine Grained ◽  
Bone Modification ◽  
Western Colorado ◽  
The Matrix ◽  
Many Sources

The Mygatt-Moore Quarry is a deposit of several thousand dinosaur bones in the Brushy Basin Member of the Morrison Formation in western Colorado. The site has been worked for more than 30 years and nearly 2400 mapped specimens have been collected. This study gathered data about the quarry from many sources to investigate the origin of the deposit. The Mygatt-Moore Quarry appears to be an attritional deposit of a relatively restricted diversity of dinosaurs, with few other non-dinosaurian taxa, that accumulated in a vernal pool deposit in an overbank setting. Bone modification was mostly by corrosion and breakage by trampling; scavenging was abundant. The paleofauna is dominated by Allosaurus and Apatosaurus (MNI and NIS), with the polacanthid ankylosaur Mymoorapelta less common. The matrix of the main quarry layer includes abundant carbonized fragments of plant material, and the mud during the time of deposition may have been often at least damp and occasionally acidic and dysoxic. The Cleveland-Lloyd Dinosaur Quarry is a close correlate of the Mygatt-Moore Quarry in terms of lithology and taphonomy, but demonstrates significant differences upon close inspection of matrix details and bone modification. Large quarries of fine-grained facies in the Morrison Formation possess a very different preservation mode as well as different taxon and relative abundance profiles from those in coarser sediments, which suggests that more may be learned in the future from taphofacies study of large quarries in mudstone beds.

scholarly journals The Morrison Formation Extinct Ecosystems Project

1996 ◽  
Vol 20 ◽  
pp. 20-27
Author(s):  
Christine Turner ◽  
Fred Peterson ◽  
D. Chure ◽  
T. Demko ◽  
G. Engelmann
Keyword(s):  
United States ◽  
Late Jurassic ◽  
The United States ◽  
Upper Jurassic ◽  
Morrison Formation

The Morrison Project is a multidisciplinary effort to interpret the ancient ecosystem that was present in the Western Interior of the United States during deposition of the Upper Jurassic Morrison Formation. The project began in June of 1994 and the first two years of research (1994-95, 1995-96) were devoted primarily to identifying problems and gathering information that would form the basis for later interpretations. Efforts during the final year (1996-97) were directed toward resolving remaining problems or conflicting findings and synthesizing the various research endeavors into a reconstruction of the Late Jurassic ecosystem.

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