Redescription of <i>Ankylosaurus magniventris </i>Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America

Carpenter, Kenneth

doi:10.1139/e04-043

Cited by 82 publications

(155 citation statements)

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“…Some of the diagnostic characters Carpenter (2004) identified are also present in closely related ankylosaurins, which we comment on here. A posterodorsolaterally directed squamosal horn, posteroventrolaterally directed quadratojugal horn, and cranial ornamentation divided into polygons are present in all Laramidian ankylosaurins, not just Ankylosaurus (Fig.…”

Section: Arbour and Mallonmentioning

confidence: 93%

“…We offer new observations concerning the cranial and postcranial anatomy of Ankylosaurus not already presented by Carpenter (2004). We describe previously unidentified and undescribed elements of the holotype, AMNH 5895, and of the largest specimen, CMN 8880.…”

Section: Introductionmentioning

confidence: 99%

“…A high-quality cast of this skull, made available by Research Casting International, is accessioned at the University of Alberta Laboratory for Vertebrate Paleontology (UALVP 54722) and was used as an additional reference for this specimen. CMN 8880 was briefly described and figured by Carpenter (2004), who suggested that the skull roof was poorly preserved. However, the skull was stored upside down at the time so that the dorsal surface may have been unavailable for examination.…”

Section: Methodsmentioning

confidence: 99%

“…The tail club of AMNH 5214 is inaccessibly mounted at an angle behind glass, but some length measurements were acquired using a measuring tape laid flush with the glass and a laser pointer squared to the glass. Other measurements for this tail club were estimated using ImageJ (Rasband 2017) and figures in Carpenter (2004) cross-referenced with measurements of the mounted specimen.…”

Section: Methodsmentioning

confidence: 99%

“…Nevertheless, these remains indicate that Ankylosaurus had diverged from the Laramidian ankylosaurine bauplan to a surprising degree, particularly with regards to its narial anatomy and body size. Carpenter (2004) was the last to review Ankylosaurus anatomy in detail, but a bevy of recent ankylosaurid finds (e.g., Loewen et al 2013;Arbour et al 2014a;Arbour and Evans 2017), new insights into ankylosaur anatomy and relationships (Witmer and Ridgely 2008;Thompson et al 2012;Hill et al 2015;Leahey et al 2015;Arbour and Currie 2016), and novel information gleaned from historical specimens warrant a re-evaluation of the genus that we present here.…”

Section: Introductionmentioning

confidence: 99%

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Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris

Arbour

Mallon

2017

FACETS

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Ankylosaurus magniventris is an iconic dinosaur species often depicted in popular media. It is known from relatively fragmentary remains compared with its earlier and smaller relatives such as Euoplocephalus and Anodontosaurus. Nevertheless, the known fossils of Ankylosaurus indicate that it had diverged significantly in cranial and postcranial anatomy compared with other Laramidian ankylosaurines. In particular, the dentition, narial region, tail club, and overall body size differ substantially from other Campanian-Maastrichtian ankylosaurines. We review the anatomy of this unusual ankylosaur using data from historic and newly identified material and discuss its palaeoecological implications.

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Section: Arbour and Mallonmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris

Arbour

Mallon

2017

FACETS

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Evolution of the Dinosauriform Respiratory Apparatus: New Evidence from the Postcranial Axial Skeleton

Schachner

Farmer

McDonald

et al. 2011

The Anatomical Record

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Examination of the thoracic rib and vertebral anatomy of extant archosaurs indicates a relationship between the postcranial axial skeleton and pulmonary anatomy. Lung ventilation in extant crocodilians is primarily achieved with a hepatic piston pump and costal rotation. The tubercula and capitula of the ribs lie on the horizontal plane, forming a smooth thoracic ''ceiling'' facilitating movement of the viscera. Although the parietal pleura is anchored to the dorsal thoracic wall, the dorsal visceral pleura exhibits a greater freedom of movement. The air sac system and lungs of birds are associated with bicapitate ribs with a ventrally positioned capitular articulation, generating a rigid and furrowed rib cage that minimizes dorsoventral changes in volume in the dorsal thorax. The thin walled bronchi are kept from collapsing by fusion of the lung to the thorax on all sides. Data from this study suggest a progression from a dorsally rigid, heterogeneously partitioned, multichambered lung in basal dinosauriform archosaurs towards the small entirely rigid avian-style lung that was likely present in saurischian dinosaurs, consistent with a constant volume cavum pulmonale, thin walled parabronchi, and distinct air sacs. There is no vertebral evidence for a crocodilian hepatic piston pump in any of the taxa reviewed. The evidence for both a rigid lung and unidirectional airflow in dinosauriformes raises the possibility that these animals had a highly efficient lung relative to other Mesozoic vertebrates, which may have contributed to their successful radiation during this time period. Anat Rec, 294:1532Rec, 294: -1547Rec, 294: , 2011. V C 2011 Wiley-Liss, Inc.Key words: lung morphology; respiration; Archosauria; postcranial skeleton; dinosauriformesAs the sole surviving members of Archosauria, crocodilians and birds are the best extant models for reconstructing the soft tissue anatomy and physiological state of their extinct relatives. However, for features that are disparate in these terminal taxa, it is difficult to infer their evolutionary history in extinct archosaurs, a problem compounded by the lack of a fossil record for many of these features. The interesting questions of the origin of endothermy, aerobic capacity, and the evolution of the avian respiratory system have been particularly troublesome in this regard and addressing these questions necessitates the use of extant phylogenetic

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A review and reappraisal of the specific gravities of present and past multicellular organisms, with an emphasis on tetrapods

Larramendi¹,

Paul

Hsu³

2020

The Anatomical Record

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The density, or specific gravity (SG), of organisms has numerous important implications for their form, function, ecology, and other facets of beings living and dead, and it is especially necessary to apply SG values that are as accurate as practical when estimating their masses which is itself a critical aspect of living things. Yet a comprehensive review and analysis of this notable subject of anatomy has never been conducted and published. This is such an effort, being as extensive as possible with the data on hand, bolstered by some additional observations, and new work focusing on extinct animals who densities are least unknown: pterosaurs and dinosaurs with extensive pneumatic complexes, including the most sophisticated effort to date for a sauropod. Often difficult to determine even via direct observation, techniques for obtaining the best possible SG data are explained and utilized, including observations of floating animals. Neutral specific gravity (NSG) is proposed as the most important value for tetrapods with respiratory tracts of fluctuating volume. SGs of organisms range from 0.08 to 2.6, plant tissues from 0.08 to 1.39, and vertebrates from about 0.75 (some giant pterosaurs) to 1.2 (those with heavy armor and/or skeletons). Tetrapod NSGs tend to be somewhat higher than widely thought, especially those theropod and sauropod dinosaurs and pterosaurs with air‐sacs because respiratory system volume is usually measured at maximum inhalation in birds. Also discussed is evidence that the ratio of the mass of skeletons relative to total body mass has not been properly assayed in the past.

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Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America

Cited by 82 publications

References 11 publications

Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris

Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris

Evolution of the Dinosauriform Respiratory Apparatus: New Evidence from the Postcranial Axial Skeleton

A review and reappraisal of the specific gravities of present and past multicellular organisms, with an emphasis on tetrapods

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