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{{Short description|Extinct genus of reptiles}}
{{Automatic taxobox
{{Speciesbox
| fossil_range = {{fossil range|Middle Jurassic|170}}
| fossil_range = [[Middle Jurassic]], {{fossil range|Toarcian}}
⚫
| authority = Wilberg, [[2015 in paleontology|2015]]
| type_species = {{extinct}}'''''Zoneait nargorum'''''
| image = Zoneait holotype2.png
| image_caption = Holotype specimen{{refn|group=nb|The pictured elements of the holotype include: A, a partial vertebra (PAL256444); B, a partial vertebra (PAL256442); C, a partial rostrum (PAL244292); D, the right proximal end of a humerus (PAL256441); E, a partial vertebra (PAL256443); F, a partial antorbital (PAL244476)}}
⚫
| type_species_authority = Wilberg, 2015
| display_parents = 3
| genus = Zoneait
⚫
| parent_authority = Wilberg, [[2015 in paleontology|2015]]
| species = nargorum
⚫
| authority = Wilberg, 2015
}}
}}


'''''Zoneait''''' (pronounced "zone-eight" and meaning "large tooth" in the [[Kiowa]] language) is an extinct [[genus]] of [[thalattosuchia]]n [[crocodylomorph]] known from a single species, '''''Zoneait nargorum''''', from the [[Middle Jurassic]] of Oregon. ''Z. nargorum'' was named in 2015 by paleontologist Eric Wilberg on the basis of several partial skulls, vertebrae, and forelimb bones that were found in an outcrop of the [[Snowshoe Formation]] near the town of [[Izee, Oregon|Izee]]. It is currently the oldest known member of [[Metriorhynchoidea]], a [[clade]] of marine-adapted thalattosuchians that existed until the [[Early Cretaceous]]. The skeleton of ''Zoneait'' possesses several adaptations for offshore marine life but retains features characteristic of its land-living ancestors, indicating that it is a [[transitional form]] between the fully marine [[metriorhynchid]]s of the Late Jurassic and Early Cretaceous and earlier non-marine crocodylomorphs. The Snowshoe Formation was deposited in a shallow marine environment within a tropical [[forearc basin]], suggesting that ''Zoneait'' was a marine predator.<ref name=WEW15>{{cite doi|10.1080/02724634.2014.902846}}</ref>
'''''Zoneait''''' (pronounced "zone-eight" and meaning "large tooth" in the [[Kiowa]] language) is an extinct [[genus]] of [[thalattosuchia]]n [[crocodylomorph]] known from a single species, '''''Zoneait nargorum''''', from the [[Middle Jurassic]] [[Snowshoe Formation]] of [[Oregon]].


== Discovery and naming ==
⚫
Although ''Zoneait'' is the oldest metriorhynchoid, [[phylogenetic analysis]] indicates that the slightly younger taxa ''[[Eoneustes]]'' and ''[[Teleidosaurus]]'' are more [[basal (phylogenetics)|basal]] than it. Wilberg found that ''Zoneait'' is the [[sister taxon]] of Metriorhynchidae, which suggests that it should have been more extensively adapted to marine life than ''Teleidosaurus'' and ''Eoneustes'' were, but less adapted than true metriorhynchids like ''[[Metriorhynchus]]'' and ''[[Cricosaurus]]'', which were fully marine. ''Zoneait'' has a streamlined skull with eyes that faced laterally like those of metriorhychids, unlike the more upward-facing eyes of ''Teleidosaurus'' and other non-marine aquatic crocodylomorphs. The shift in eye orientation is thought to reflect changes in feeding ecology; upward-facing eyes would have been adaptive for aquatic crocodylomorphs ambushing land-living prey from beneath the surface of the water, whereas side-facing eyes would have been adaptive for marine crocodylomorphs hunting in open marine environments. The skull of ''Zoneait'' also shows evidence of [[salt gland]]s in the form of enlarged passageways for the [[Common carotid artery|carotid artery]], which would have increased bloodflow to the glands. The forelimbs are not flattened into paddles as in metriorhynchids, but the [[ulna]] (lower arm bone) is reduced in length, indicating that forelimb reduction began at the lower limb and progressed upward (the [[humerus]] or upper arm bone of ''Zoneait'' not reduced). Taken together, the transitional features of ''Zoneait'' indicate that metriorhynchoids' adaptation of a marine lifestyle began with a shift in feeding ecology and only later involved changes in swimming locomotion.<ref name=WEW15/>
The holotype was collected by Lupher and Packard,<ref>[[Éric Buffetaut|Buffetaut]]. (1979). Jour.Paleontology. 53,pt.1: 210, tf.2f,g.</ref> and ''Z. nargorum'' was named in 2015 by paleontologist Eric Wilberg on the basis of several partial skulls, vertebrae, and forelimb bones that were found in an outcrop of the Weberg Member of the [[Snowshoe Formation]] near the town of [[Izee, Oregon|Izee]].<ref name="WEW15" /> It is a member of [[Metriorhynchoidea]], a [[clade]] of marine-adapted thalattosuchians that existed until the [[Early Cretaceous]].

== Description and classification ==
The skeleton of ''Zoneait'' possesses several adaptations for offshore marine life but retains features characteristic of its land-living ancestors, indicating that it is a [[transitional form]] between the fully marine [[metriorhynchid]]s of the late Middle Jurassic to Early Cretaceous, and earlier non-marine crocodylomorphs. The Snowshoe Formation was deposited in a shallow marine environment within a tropical [[forearc basin]], suggesting that ''Zoneait'' was a marine predator.<ref name="WEW15">{{Cite journal | doi = 10.1080/02724634.2014.902846| title = A new metriorhynchoid (Crocodylomorpha, Thalattosuchia) from the Middle Jurassic of Oregon and the evolutionary timing of marine adaptations in thalattosuchian crocodylomorphs| journal = Journal of Vertebrate Paleontology| volume = 35| issue = 2| pages = e902846| year = 2015| last1 = Wilberg | first1 = E. W. | bibcode = 2015JVPal..35E2846W| s2cid = 83587692| url = https://figshare.com/articles/dataset/A_new_metriorhynchoid_Crocodylomorpha_Thalattosuchia_from_the_Middle_Jurassic_of_Oregon_and_the_evolutionary_timing_of_marine_adaptations_in_thalattosuchian_crocodylomorphs/1313001}}</ref>

Wilberg found that ''Zoneait'' is the [[sister taxon]] of Metriorhynchidae, which suggests that it should have been more extensively adapted to marine life than ''[[Teleidosaurus]]'' and ''[[Eoneustes]]'' were, but less adapted than true metriorhynchids like ''[[Metriorhynchus]]'' and ''[[Cricosaurus]]'', which were fully marine. The skull of ''Zoneait'' has expanded prefrontals, which support laterally-facing eyes. In combination with a streamlined skull, which is notably more derived than other non-metriorhynchid members of Metriorhynchoidea.

== Paleoecology ==
⚫
The lateral-facing eyes of ''Zoneait'', which are similar to those of metriorhynchids, differentiate it from non-marine aquatic crocodylomorphs, which have more upward-facing eyes. The shift in eye orientation is thought to reflect changes in feeding ecology; upward-facing eyes would have been adaptive for aquatic crocodylomorphs ambushing land-living prey from beneath the surface of the water, whereas side-facing eyes would have been adaptive for marine crocodylomorphs hunting in open marine environments. The forelimbs are not flattened into paddles as in metriorhynchids, but the [[ulna]] (lower arm bone) is reduced in length, indicating that forelimb reduction began at the lower limb and progressed upward (the [[humerus]] or upper arm bone of ''Zoneait'' not reduced). Taken together, the transitional features of ''Zoneait'' indicate that metriorhynchoids' adaptation of a marine lifestyle began with a shift in feeding ecology and only later involved changes in swimming locomotion.<ref name="WEW15" />

==Notes==
{{reflist|group=nb}}


==References==
==References==
{{reflist}}
{{Reflist}}


{{portal|Palaeontology}}
{{Portal|Palaeontology}}


{{Thalattosuchia}}
{{Thalattosuchia}}
{{Taxonbar|from1=Q20080503|from2=Q124462827}}


[[Category: Marine crocodylomorphs]]
[[Category:Jurassic animals of North America]]
[[Category: Middle Jurassic crocodylomorpha]]
[[Category:Monotypic prehistoric reptile genera]]
[[Category:Prehistoric marine crocodylomorphs]]
[[Category:Middle Jurassic crocodylomorphs]]
[[Category:Fossil taxa described in 2015]]
[[Category:Fossil taxa described in 2015]]
[[Category:Thalattosuchians]]
[[Category:Paleontology in Oregon]]
[[Category:Prehistoric pseudosuchian genera]]

Latest revision as of 05:24, 12 November 2024

Zoneait
Temporal range: Middle Jurassic, Toarcian
Holotype specimen[nb 1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Crocodyliformes
Suborder: †Thalattosuchia
Superfamily: †Metriorhynchoidea
Clade: †Euthalattosuchia
Genus: †Zoneait
Wilberg, 2015
Species:
†Z. nargorum
Binomial name
†Zoneait nargorum
Wilberg, 2015

Zoneait (pronounced "zone-eight" and meaning "large tooth" in the Kiowa language) is an extinct genus of thalattosuchian crocodylomorph known from a single species, Zoneait nargorum, from the Middle Jurassic Snowshoe Formation of Oregon.

Discovery and naming

[edit]

The holotype was collected by Lupher and Packard,[1] and Z. nargorum was named in 2015 by paleontologist Eric Wilberg on the basis of several partial skulls, vertebrae, and forelimb bones that were found in an outcrop of the Weberg Member of the Snowshoe Formation near the town of Izee.[2] It is a member of Metriorhynchoidea, a clade of marine-adapted thalattosuchians that existed until the Early Cretaceous.

Description and classification

[edit]

The skeleton of Zoneait possesses several adaptations for offshore marine life but retains features characteristic of its land-living ancestors, indicating that it is a transitional form between the fully marine metriorhynchids of the late Middle Jurassic to Early Cretaceous, and earlier non-marine crocodylomorphs. The Snowshoe Formation was deposited in a shallow marine environment within a tropical forearc basin, suggesting that Zoneait was a marine predator.[2]

Wilberg found that Zoneait is the sister taxon of Metriorhynchidae, which suggests that it should have been more extensively adapted to marine life than Teleidosaurus and Eoneustes were, but less adapted than true metriorhynchids like Metriorhynchus and Cricosaurus, which were fully marine. The skull of Zoneait has expanded prefrontals, which support laterally-facing eyes. In combination with a streamlined skull, which is notably more derived than other non-metriorhynchid members of Metriorhynchoidea.

Paleoecology

[edit]

The lateral-facing eyes of Zoneait, which are similar to those of metriorhynchids, differentiate it from non-marine aquatic crocodylomorphs, which have more upward-facing eyes. The shift in eye orientation is thought to reflect changes in feeding ecology; upward-facing eyes would have been adaptive for aquatic crocodylomorphs ambushing land-living prey from beneath the surface of the water, whereas side-facing eyes would have been adaptive for marine crocodylomorphs hunting in open marine environments. The forelimbs are not flattened into paddles as in metriorhynchids, but the ulna (lower arm bone) is reduced in length, indicating that forelimb reduction began at the lower limb and progressed upward (the humerus or upper arm bone of Zoneait not reduced). Taken together, the transitional features of Zoneait indicate that metriorhynchoids' adaptation of a marine lifestyle began with a shift in feeding ecology and only later involved changes in swimming locomotion.[2]

Notes

[edit]
  1. ^ The pictured elements of the holotype include: A, a partial vertebra (PAL256444); B, a partial vertebra (PAL256442); C, a partial rostrum (PAL244292); D, the right proximal end of a humerus (PAL256441); E, a partial vertebra (PAL256443); F, a partial antorbital (PAL244476)

References

[edit]
  1. ^ Buffetaut. (1979). Jour.Paleontology. 53,pt.1: 210, tf.2f,g.
  2. ^ a b c Wilberg, E. W. (2015). "A new metriorhynchoid (Crocodylomorpha, Thalattosuchia) from the Middle Jurassic of Oregon and the evolutionary timing of marine adaptations in thalattosuchian crocodylomorphs". Journal of Vertebrate Paleontology. 35 (2): e902846. Bibcode:2015JVPal..35E2846W. doi:10.1080/02724634.2014.902846. S2CID 83587692.
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