Tyler Greenfield- Bachelor of Arts
- Graduate student at University of Wyoming
Tyler Greenfield
- Bachelor of Arts
- Graduate student at University of Wyoming
About
22
Publications
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Introduction
I am a paleontologist who studies chondrichthyans, dinosaurs, and cephalopods, with a focus on their taxonomy and nomenclature. I also study the history of paleontology, paleoart, and cryptozoology.
Skills and Expertise
Current institution
Publications
Publications (22)
The megalodon, Otodus megalodon, is arguably the most renowned ancient shark because of its extreme size and carnivorous nature. Paleontologists overwhelmingly agree that it went extinct towards the end of the Pliocene. However, some cryptozoologists have proposed that it never died out. Their evidence for its modern survival consists of alleged po...
Convergent evolution is the development of analogous structures or bauplans in at least two independent lineages of organisms. Convergence is driven by the occupation of similar ecological niches and by various physical and phylogenetic constraints (McGhee, 2011). Despite the wide recognition of this phenomenon in evolutionary biology, formal terms...
New information about Mitchill's monster is added to what was published previously (Greenfield, 2023a). The claim that the specimen was housed at the University of North Carolina is investigated. Its possible connection with modern shark sightings is also examined.
Capasso et al. (2024) reported an exceptionally large rostrum of the sawskate Onchopristis sp. from the Maastrichtian Dakhla Formation of Egypt. They also described four isolated lateral rostral denticles which were referred to the same taxon. However, here it is demonstrated that neither can be assigned to Onchopristis; the rostrum is Sclerorhynch...
Recorded presentation:
https://www.youtube.com/watch?v=_2CZMfyHQAM&t=528s
As one of the Old Masters of paleoart, Charles R. Knight created many iconic depictions of prehistoric animals that inspired countless successors and imitators. Among his signature pieces is his 1897 painting of the ceratopsid dinosaur Agathaumas sphenocerus. Knight’s Agathaumas strikes a regal pose, decked out in a suit of armor plating and brimmi...
Saws are elongated rostra with enlarged denticles that are used for hunting and feeding. They convergently evolved in three groups of sharks and rays, the extinct sawskates and the extant sawsharks and sawfishes. Saws and saw-bearing fishes are briefly reviewed here, including their anatomy, ecology, and phylogeny. The term 'pristification' is prop...
As one of the Old Masters of paleoart, Charles R. Knight created many iconic depictions of prehistoric animals that inspired countless successors and imitators. Among his signature pieces is his 1897 painting of the ceratopsid dinosaur Agathaumas sphenocerus. Knight’s Agathaumas strikes a regal pose, decked out in a suit of armor plating and brimmi...
In 1818, Samuel L. Mitchill briefly detailed a fossil vertebral column with teeth found in North Carolina. It was believed to have been a sea serpent or giant shark and it was lost in a museum fire in 1866. Its true identity is difficult to ascertain with the sparse information and absence of illustrations. This specimen, dubbed 'Mitchill's monster...
More specimens are added to the list of skeletal material from megatooth sharks. These include one of the most complete otodontids to date, an exceptional skeleton of Cretalamna with preserved soft tissues. It has important implications for the body form and phylogenetic position of otodontids. Criticisms of the Lamnoidea hypothesis by Shimada (202...
Woodward (1895: 5) named Galeocerdo jaekeli for three teeth from the Santonian-Campanian Chalk Group of England. He initially considered it a predecessor to the extant tiger shark, Galeocerdo cuvier (Peron & Lesueur in Lesueur, 1822), and a member of the family ‘Carchariidae’ Müller & Henle, 1838 (= Carcharhinidae Jordan & Evermann, 1896). He later...
Otodontidae is a family of extinct sharks, commonly known as the megatooths, that includes the iconic Otodus megalodon. While isolated teeth are their most abundant fossils, rarer elements of the cranial and postcranial skeleton have also been recovered. Rostral nodes, jaws, and vertebrae are among these elements. This paper presents the first list...
The name of the lamniform shark genus Archaeolamna Li, 1997 is preoccupied by Archaeolamna Siverson, 1992. The new name Lilamna Greenfield, nom. nov. is proposed to replace the junior homonym, resulting in the new combination Lilamna apophysata (Li, 1997), comb. nov.
The sawskates, suborder Sclerorhynchoidei Cappetta, 1980, are divided into five families currently known as Ischyrhizidae Cope, 1875, Sclerorhynchidae Arambourg, 1952, Schizorhizidae Kirkland & Aguillón-Martínez, 2002 (stat. nov.), Ptychotrygonidae Kriwet et al., 2009, and Onchopristidae Villalobos-Segura et al., 2021. For Sclerorhynchidae in parti...
The megatooth sharks, family Otodontidae, have a complicated taxonomic history. The latest debate concerns the genera Otodus Agassiz, 1838 and Carcharocles Jordan & Hannibal in Jordan, 1923. It is argued either to use Otodus for the whole obliquus-megalodon anagenetic lineage (Shimada et al. 2017) or to split it into Otodus and Carcharocles based o...
Until now, authorship of the sauropodomorph dinosaur genus Coloradisaurus has been attributed to Lambert, 1983. Here we demonstrate that Lambert’s work does not meet the requirements of Articles 13.1 and 13.3 of the Code for availability of this name, therefore it is a nomen nudum in that publication. Instead, it was inadvertently made available a...
