Post by creature386 on Aug 29, 2020 23:06:10 GMT 5
Egoria malashichevi
Artistic reconstruction of Egoria malashichevi by Pavel Skutschas
Temporal range: Bathonian (Middle Jurassic; 168.3-166.1 Ma)
Location: Berezovsk Quarry (Western Siberia, China)
Scientific classification:
Animalia
Chordata
Amphibia
Caudata
Egoria
E. malashichevi
Description:
Egoria malashichevi was a species of salamander-like amphibian from the Middle Jurassic of Siberia, specifically the Berezovsk Quarry. It is known from a fragmented holotype consisting of three thoracic and one caudal vertebrae. The Berezovsk outcrop had been known to contain various species of stem-salamanders before, but the material assigned to E. malashichevi is diagnostic enough to demonstrate that it belongs to its own taxon. Before its formal description, it was simply known as “Berezovsk salamander A”.
E. malashichevi is estimated at a body length of 18 to 21.5 cm.
The species name honors the late Yegor Malashichev who was an associate professor at the Department of Vertebrate Zoology at St Petersburg University during his lifetime.
Diagnostic criteria:
Egoria malashichevi has been diagnosed on the basis of the following criteria.
Phylogenetic position:
Egoria malashichevi is believed to have been a stem-salamander, much like its contemporary taxon Urupia monstrosa. A notable feature of stem-salamanders is their tendency towards neoteny (retaining most of their juvenile features into adulthood). Little is known about the earliest salamanders. Prior to the discovery of E. malashichevi, it had been believed that stem-salamanders had filled the niche of large water-dwellers while more derived salamanders had smaller body sizes. With its size, E. malashichevi falls firmly into the small-bodied category though.
This demonstrates how the earliest relatives of modern-day salamanders displayed a greater ecological and morphological diversity than previously believed.
Literature:
Skutschas et al. (2020) A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia. PLoS ONE 15(2): e0228610. doi:10.1371/journal.pone.0228610
Artistic reconstruction of Egoria malashichevi by Pavel Skutschas
Temporal range: Bathonian (Middle Jurassic; 168.3-166.1 Ma)
Location: Berezovsk Quarry (Western Siberia, China)
Scientific classification:
Animalia
Chordata
Amphibia
Caudata
Egoria
E. malashichevi
Description:
Egoria malashichevi was a species of salamander-like amphibian from the Middle Jurassic of Siberia, specifically the Berezovsk Quarry. It is known from a fragmented holotype consisting of three thoracic and one caudal vertebrae. The Berezovsk outcrop had been known to contain various species of stem-salamanders before, but the material assigned to E. malashichevi is diagnostic enough to demonstrate that it belongs to its own taxon. Before its formal description, it was simply known as “Berezovsk salamander A”.
E. malashichevi is estimated at a body length of 18 to 21.5 cm.
The species name honors the late Yegor Malashichev who was an associate professor at the Department of Vertebrate Zoology at St Petersburg University during his lifetime.
Diagnostic criteria:
Egoria malashichevi has been diagnosed on the basis of the following criteria.
atlantal anterior cotyles with elliptical anterior outline, located at an angle of approximately 135–137 degrees to each other; wide posterior portion of the atlantal centrum; ossified portion of the intercotylar tubercle represented by dorsal and ventral lips; absence of a deep depression on the ventral surface of the atlantal centrum; absence of pronounced ventrolateral ridges on the atlas; absence of spinal nerve foramina; presence of a pitted texture on the ventral and lateral surfaces of the centra and lateral surfaces neural arch pedicels; presence of a short atlantal neural arch with its anterior border situated behind the level of the anterior cotyles; short trunk vertebrae; and upper transverse process (= diapophysis) larger than lower transverse process (= parapophysis) on the trunk vertebrae; notochordal canal opens in the upper half of the cotyle (= the lower portion of the centrum is more massive and less compact than the upper portion)
Phylogenetic position:
Egoria malashichevi is believed to have been a stem-salamander, much like its contemporary taxon Urupia monstrosa. A notable feature of stem-salamanders is their tendency towards neoteny (retaining most of their juvenile features into adulthood). Little is known about the earliest salamanders. Prior to the discovery of E. malashichevi, it had been believed that stem-salamanders had filled the niche of large water-dwellers while more derived salamanders had smaller body sizes. With its size, E. malashichevi falls firmly into the small-bodied category though.
This demonstrates how the earliest relatives of modern-day salamanders displayed a greater ecological and morphological diversity than previously believed.
Literature:
Skutschas et al. (2020) A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia. PLoS ONE 15(2): e0228610. doi:10.1371/journal.pone.0228610