Alligator mississippiensis is only distantly related to the other extant alligator (A. sinensis), with much closer relatives known from the geologic past of North America. While A. mississippiensis is well known from the early Pleistocene and later, no Alligator was known from the middle and late Pliocene until the discovery of Haile 7C and 7G late Pliocene (~2 Ma) sites from Florida. These specimens were analyzed using a diagnostic character matrix along with systematic analyses of the results. This research upholds A. mefferdi as a valid taxon, and the utility of the species in fossil identification is further established. The Haile material cannot be placed within either of the aforementioned taxa, and a new species description is planned in a later publication. Furthermore, the systematic analysis used in this research suggests that the line leading to A. sinensis diverged before the earliest known Alligator. An Eocene dispersal of the genus into Asia is plausible.
","abstract_html":"<p><em>Alligator mississippiensis</em> is only distantly related to the other extant alligator (<em>A. sinensis</em>), with much closer relatives known from the geologic past of North America. While <em>A. mississippiensis</em> is well known from the early Pleistocene and later, no <em>Alligator</em> was known from the middle and late Pliocene until the discovery of Haile 7C and 7G late Pliocene (~2 Ma) sites from Florida. These specimens were analyzed using a diagnostic character matrix along with systematic analyses of the results. This research upholds <em>A. mefferdi</em> as a valid taxon, and the utility of the species in fossil identification is further established. The Haile material cannot be placed within either of the aforementioned taxa, and a new species description is planned in a later publication. Furthermore, the systematic analysis used in this research suggests that the line leading to <em>A. sinensis</em> diverged before the earliest known <em>Alligator</em>. An Eocene dispersal of the genus into Asia is plausible.</p>","abstract_has_math":false,"creators":["Stout, Jeremy Brett"],"institution":null,"degree_name":"MS (Master of Science)","degree_level":"Thesis - restricted","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009-12-19T08:00:00Z","date_published":"2009-12-19T08:00:00Z","updated_at":"2026-07-24T02:20:55Z","subjects":["Alligator","cladistic analysis","cranial morphology","Haile 7C","Haile 7G","Earth Sciences","Paleontology","Physical Sciences and Mathematics"],"languages":[],"rights":["Copyright by the authors."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://dc.etsu.edu/etd/1786","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Stout, Jeremy Brett"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2009-12-19T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis - restricted"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS (Master of Science)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Alligator","cladistic analysis","cranial morphology","Haile 7C","Haile 7G","Earth Sciences","Paleontology","Physical Sciences and Mathematics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Copyright by the authors."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://dc.etsu.edu/context/etd/article/3138/viewcontent/StoutJ120409f.pdf","https://dc.etsu.edu/etd/1786"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Alligator mississippiensis is only distantly related to the other extant alligator (A. sinensis), with much closer relatives known from the geologic past of North America. While A. mississippiensis is well known from the early Pleistocene and later, no Alligator was known from the middle and late Pliocene until the discovery of Haile 7C and 7G late Pliocene (~2 Ma) sites from Florida. These specimens were analyzed using a diagnostic character matrix along with systematic analyses of the results. This research upholds A. mefferdi as a valid taxon, and the utility of the species in fossil identification is further established. The Haile material cannot be placed within either of the aforementioned taxa, and a new species description is planned in a later publication. Furthermore, the systematic analysis used in this research suggests that the line leading to A. sinensis diverged before the earliest known Alligator. An Eocene dispersal of the genus into Asia is plausible.
"]},{"key":"dc:title","label":"Title","values":["Cranial Morphology and Systematics of Late Pliocene Alligator from Florida, with Notes on Alligator Evolution and Distribution."]}]}],"canonical_facts":{"dc:creator":["Stout, Jeremy Brett"],"dc:date.issued":["2009-12-19T08:00:00Z"],"dc:description.abstract":["Alligator mississippiensis is only distantly related to the other extant alligator (A. sinensis), with much closer relatives known from the geologic past of North America. While A. mississippiensis is well known from the early Pleistocene and later, no Alligator was known from the middle and late Pliocene until the discovery of Haile 7C and 7G late Pliocene (~2 Ma) sites from Florida. These specimens were analyzed using a diagnostic character matrix along with systematic analyses of the results. This research upholds A. mefferdi as a valid taxon, and the utility of the species in fossil identification is further established. The Haile material cannot be placed within either of the aforementioned taxa, and a new species description is planned in a later publication. Furthermore, the systematic analysis used in this research suggests that the line leading to A. sinensis diverged before the earliest known Alligator. An Eocene dispersal of the genus into Asia is plausible.
"],"dc:identifier":["https://dc.etsu.edu/context/etd/article/3138/viewcontent/StoutJ120409f.pdf","https://dc.etsu.edu/etd/1786"],"dc:rights":["Copyright by the authors."],"dc:subject":["Alligator","cladistic analysis","cranial morphology","Haile 7C","Haile 7G","Earth Sciences","Paleontology","Physical Sciences and Mathematics"],"dc:title":["Cranial Morphology and Systematics of Late Pliocene Alligator from Florida, with Notes on Alligator Evolution and Distribution."],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis - restricted"],"thesis:degree_name":["MS (Master of Science)"]},"updated_at":"2026-07-24T02:20:55Z"}