Andrew Milner

Andrew Milner
St. George Dinosaur Discovery Site at Johnson Farm

B.Sc.
Late Triassic-Early Jurassic faunas, floras, ichnology of American Southwest; Triassic-Jurassic transition

About

74
Publications
29,513
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
922
Citations
Additional affiliations
May 1988 - November 1989
Canadian Museum of Nature / Musée canadien de la nature
Position
  • Intern
Description
  • Late Pleistocene Champlain Sea collections under supervision of Dr. C. Richard Harington.
Education
August 1990 - September 1996
Brock University
Field of study
  • Earth Sciences/Biology

Publications

Publications (74)
Article
Full-text available
Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb....
Article
Full-text available
The Lower Jurassic Whitmore Point Member is a widespread lacustrine unit at the top of the Moenave Formation that can be traced across southwestern Utah and northeastern Arizona. The shoreline to the northeast of the outcrop belt trends northwest to southeast, and the central part of the lake is interpreted to be southwest of the outcrop belt. The...
Article
Full-text available
We present here a detailed study of the lithostratigraphy and preliminary vertebrate biostratigraphy of the Upper Triassic Chinle Formation in Lisbon Valley, southeastern Utah. Triassic salt tectonism resulted in a period of erosion and possibly non-deposition that removed the top of the Lower Permian Cutler Group, the Early-Middle Triassic Moenkop...
Article
Full-text available
The Chinle Formation and the lower part of the overlying Wingate Sandstone and Moenave Formation were deposited in fluvial, lacustrine, paludal, and eolian environments during the Norian and Rhaetian stages of the Late Triassic (~230 to 201.3 Ma), during which time the climate shifted from subtropical to increasingly arid. In southern Utah, the Shi...
Article
Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the m...
Article
Theropod dinosaurs are minor components of Late Triassic ecosystems in North America, comprising coelophysoids and various non-neotheropods from the Chinle Formation of Arizona, Utah, Colorado, and New Mexico and the Dockum Group of western Texas. By the Sinemurian (Early Jurassic), the coelophysoid “Syntarsus” kayentakatae and the large-bodied non...
Article
Full-text available
New invertebrate trace fossils from the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm (SGDS) continue to expand the ichnofauna at the site. A previously unstudied arthropod locomotory trace, SGDS 1290, comprises two widely spaced, thick, gently undulating paramedial impressions flanked externally by smal...
Chapter
Full-text available
Structure-from-motion (SfM) photogrammetry is an increasingly common component of paleontological research and fossil resources management. The three-dimensional (3D) data and the derived products allow for novel and useful avenues to engage and problem-solve with park resource managers and stakeholders. The National Park Service (NPS) is developin...
Article
Full-text available
We report the first occurrence of the track type “Chirotherium” lulli from western North America. Three specimens were discovered at the “Feather Ridge Tracksite” in the Owl Rock Member of the Chinle Formation within Bears Ears National Monument of San Juan County, Utah. The ichnospecies occurs in association with Grallator isp., Brachychirotherium...
Article
Two types of unusual concretions with similar biotic contents but markedly different shapes and distributions were found in close stratigraphic proximity within the Lower Jurassic Whitmore Point Member of the Moenave Formation in St. George, Utah. Both types of concretions formed in lacustrine sediments and contain abundant ganoid fish scales, nume...
Poster
Full-text available
In the summer of 2016, field crews from the Museums of Western Colorado (MWC) discovered a laterally extensive bone bed in the Upper Triassic Chinle Formation. The site lay within the initial boundaries of Bears Ears National Monument but was excluded following a Presidential Proclamation in late 2017. Preliminary excavations of the site began in S...
Article
Full-text available
An ostracode fauna is described from lacustrine sediments of the Hettangian, Lower Jurassic, Whitmore Point Member of the Moenave Formation. The Moenave is well known for its rich, Late Triassic?–Early Jurassic fossil record, which includes fossil fishes, stromatolites, ostracodes, spinicaudatans, and a diverse ichnofauna of invertebrates and verte...
Article
The Late Triassic is a period of abrupt climate change associated with a disruption to the global carbon cycle usually ascribed to the emplacement of the Central Atlantic Magmatic Province (CAMP). Geochronologic, paleontologic, and geochemical studies have shown that the CAMP was likely the major factor for the end-Triassic extinction (ETE), howeve...
Article
Full-text available
A macrophotography technique coupled with focus stacking was used to produce source images for photogrammetry of two isolated fossil teeth from the Lower Jurassic Kayenta Formation of southwest Utah. The crown heights of the teeth are approximately 4 mm and 9 mm. The macrophotography was conducted using a Canon digital camera body with a 24-megapix...
Article
Full-text available
The Chinle Formation and the lower part of the overlying Wingate Sandstone and Moenave Formation were deposited in fluvial, lacustrine, paludal, and eolian environments during the Norian and Rhaetian stages of the Late Triassic (~230 to 201.3 Ma), during which time the climate shifted from subtropical to increasingly arid. In southern Utah, the Shi...
Poster
The end-Permian extinction was the largest such event in earth history and resulted in the ecologic restructuring of both terrestrial and marine environments. The dynamics and timing of marine ecologic recovery following this event has been the subject of numerous studies incorporating body and trace fossils. We report a relatively low diversity ic...
Book
In February 2000, while excavating his property in St. George, Utah, Sheldon Johnson turned over a piece of ground and discovered a fully preserved dinosaur footprint. That track was the first of many fossils to be uncovered. Five years later, the St. George Dinosaur Discovery Site at Johnson Farm was established to preserve one of the richest and...
Conference Paper
Full-text available
The Nugget Sandstone of northern Utah, along with the Navajo and Aztec sandstones to the south, was deposited as part of a vast sand sea. Although these Triassic-Jurassic erg deposits generally lack body fossils, vertebrate and invertebrate trace fossils are more common and can be locally abundant. In northern Utah the Nugget preserves a diverse ve...
Article
Full-text available
In this article, the remains of a nearly complete specimen of the enigmatic Sanmiguelia Brown plant (narrow stem and attached palm-like leaves) are described from the Early Jurassic (Hettangian) in the uppermost part of the Whitmore Point Member of the Moenave Formation in southwestern Utah. Previously, the fossil was only known from Upper Triassic...
Article
Full-text available
Tracks attributable to hopping vertebrates are rare in the fossil record. However, where they occur they are highly distinctive and easily differentiated from the tracks of other vertebrates that used different gaits. Among the groups of small extant vertebrates that hop, frogs, certain rodents, and some birds are well known. Trackways of two of th...
Conference Paper
Full-text available
The Lower-Middle Triassic Moenkopi Formation of the Colorado Plateau preserves a high-diversity track assemblage (e.g., Chirotherium, Rotodactylus, Rhynchosauroides) produced by a variety of reptilian trackmakers. Many of these trackmakers are not represented by skeletal remains and therefore they are an important record of Early Triassic reptilian...
Article
A large arthropod trackway from the Cap-aux-Os Member of the Battery Point Formation (Gaspé Sandstone Group, Middle Devonian), from the Baie de Gaspé, eastern Canada, is described and assigned to the ichnotaxon Palmichnium (= Paleohelcura) antarcticum (Gevers et al., 1971). A large stylonurid eurypterid or scorpion is considered the most likely pro...
Data
Description of characters used in the phylogenetic analysis of Iguanodontia. (0.07 MB DOC)
Data
List of the references cited in the character and specimen lists. (0.05 MB DOC)
Data
Data matrix used in the phylogenetic analysis of Iguanodontia. (0.12 MB XLS)
Data
List of the fossil specimens examined firsthand and references used to code the 61 taxa in the phylogenetic analysis of Iguanodontia. (0.03 MB XLS)
Article
Full-text available
Basal iguanodontian dinosaurs were extremely successful animals, found in great abundance and diversity almost worldwide during the Early Cretaceous. In contrast to Europe and Asia, the North American record of Early Cretaceous basal iguanodonts has until recently been limited largely to skulls and skeletons of Tenontosaurus tilletti. Herein we des...
Article
Full-text available
The name Timpoweap Member of the Moenkopi Formation has long been applied to the lowermost stratigraphic interval (mostly limestone and shale of marine origin) of the Moenkopi Formation in southwestern Utah. We describe in detail a section (lectostratotype) of the Timpoweap Member in Timpoweap Canyon near Hurricane, Utah. At this section, the Timpo...
Article
Full-text available
Bird and mammal tracks from the White Narrows Formation (early Pliocene) in the Moapa area, near Glendale, Nevada, have been known and collected for several decades, furnishing at least four museums with representative specimens. This easily accessible site contains the best Nevadan examples of early Pliocene ungulate and carnivore tracks. One carn...
Article
Full-text available
Plant fossils from the Owl Rock or Church Rock members (middle Norian) of the Chinle Formation on the Colorado Plateau are uncommon, with few localities and specimens documented to date. Here I describe three new specimens consisting of a fragmentary cf. Neocalamites stem section, a fern frond identified as cf. Cynepteris, and a bennettitalean pinn...
Article
Full-text available
3 471 North 100 West, St. George, UT 84770 Abstract—Well-preserved theropod tracks from a newly discovered Lower Jurassic, Moenave Formation site in St. George Utah, are mostly assigned to the dinosaurian ichnogenera Eubrontes and Grallator, with some assigned to cf. Gigandipus, cf. Kayentapus, and Anomoepus. The non-dinosaurian ichnogenera Batrach...
Article
Full-text available
The Hettangian Whitmore Point Member of the Moenave Formation consists of strata that record an extensive lacustrine system referred to as Lake Dixie. The Lake Dixie fish fauna has tripled in overall diversity since the discovery in 2000 of abundant fossil fish at the St. George Dinosaur Discovery Site at Johnson Farm (SGDS) and surrounding areas i...
Article
Full-text available
Early Jurassic (early Hettangian) dinosaur tracks, as well as invertebrate traces and bone material, are preserved in marginal lacustrine deposits of the Whitmore Point Member of the Moenave Formation near the St. George Dinosaur Discovery Site at Johnson Farm (SGDS), within St. George city limits in southwestern Utah. A laterally extensive, 30 cm...
Article
Full-text available
The spectacular rocks exposed in the Kolob Canyons District of Zion National Park in southwestern Utah include fossiliferous units of the Early Triassic Moenkopi Formation. The extensive exposures of this formation in the cliffs of the Kolob Canyons provide important information about the early Triassic and contain the earliest Mesozoic vertebrate...
Article
Full-text available
Conchostracans from the Lower Jurassic Whitmore Point Member of the Moenave Formation at Johnson Farm, southwestern Utah, are preserved as three-dimensional, carbonate-replaced shells. The presence of numerous, closely-spaced growth lines that extend onto the umbo, no evident sculpture, and the absence of nodes, spines or a recurved posterior margi...
Article
Full-text available
Two mapped tracksites in the Kayenta Formation are briefly described and added to the growing list of theropod dominated tracksites from the Washington County region of southwestern Utah. The largest site, with more than 200 Eubrontes tracks mostly oriented toward the south and south-southwest, is stratigraphically located at the top of the Springd...