Nephrolenellus is an extinctgenus of trilobite, fossil marine arthropods, of relatively small size (sagittal length of cephalon rarely exceeds 11 mm). Currently two species are attributed to it. Nephrolenellus lived at the end of the Lower Cambrian. Species are known from the Great Basin of California, Nevada and Arizona, with one specimen from Canada.[2]
Nephrolenellus
Temporal range: Toyonian (Upper Olenellus-zone) 516–513 Ma
N. geniculatus may have been a direct descendant of N. multinodus.[2]
Distributionedit
Nephrolenellus multinodus occurs in the late Lower Cambrian of California (Toyonian, Pyramid Shale Member, Carrara Formation, Inyo County, 35.8° N, 116.2° W).[3] and of Nevada (Toyonian, Lincoln County; and C-Shale Member, Pioche Formation, Ruin Wash, Chief Range, 37.8° N, 114.6° W).[4]
Descriptionedit
A drawing of the cephalon of Nephrolenellus geniculatusA drawing of the cephalon of Nephrolenellus multinodus
As with most early trilobites, Nephrolenellus has an only thinly calcified exoskeleton. Although most of the body is rather flat, the frontal lobe (L4) of the central area of the cephalon (or glabella) is raised, but not bulbous, and does not overlap the border at the front in dorsal view. It also has the crescent-shaped eye ridges typical for the earliest trilobites. As part of the Olenellina suborder, Nephrolenellus lacks dorsal sutures. Like all other members of the Olenelloidea superfamily, the eye-ridges spring from the back of the frontal lobe (L4) of the glabella. Typically for Nephrolenellus the eyeridges are pointing backwards and significantly (45°) outwards (along the tangent between the base and termination). The glabella is strongly hourglass-shaped, very much constricted at the second pair of side lobes (L2). The furrow between the second and third pair of lobes (S2) is transverse or gently convex anteriorly. S3 is pit-like and isolated from furrow defining the glabella (or axial furrow). The spine at the outer backside of the cephalon is longer than the most backward lobe of the glabella (also called occipital ring or L0), and it is based at point the cephalon is at its widest. The prothorax consist of thirteen segments, and the third segments has enlarged side lobes (or pleural lobes) that each carry trailing spine at the side that is comparable in length to the entire exoskeleton. It lacks the long axial spine where prothorax ends. The portion of the thorax where the pleural lobes are reduced (or opisthothorax) consist of at least 23 segments.
Referencesedit
^Lieberman, B.S. (1999). "Systematic Revision of the Olenelloidea (Trilobita, Cambrian)" (PDF). Bulletin of the Peabody Museum of Natural History. 45.
^ abcM., Webster (2007). "Ontogeny and evolution of the early Cambrian trilobite genus Nephrolenellus (Olenelloidea)". Journal of Paleontology. 81 (6): 1168–1193. Bibcode:2007JPal...81.1168W. doi:10.1666/06-092.1. S2CID 85652241.
^E.D. Fowler (1999). Biostratigraphy of upper Dyeran strata of the Carrara Formation, Emigrant Pass, Nopah Range, California. Laurentia 99: V field conference of the Cambrian Stage Subdivision Working Group, International Subcomission on Cambrian Stratigraphy. pp. 46–50.
^Palmer, A.R. (1998). "Terminal Early Cambrian Extinction of the Olenellina: Documentation from the Pioche Formation, Nevada". Journal of Paleontology. 72 (4): 650–672. Bibcode:1998JPal...72..650P. doi:10.1017/S0022336000040373. JSTOR 1306693. S2CID 131861504.
This Redlichiida-related article is a stub. You can help Wikipedia by expanding it.
nephrolenellus, extinct, genus, trilobite, fossil, marine, arthropods, relatively, small, size, sagittal, length, cephalon, rarely, exceeds, currently, species, attributed, lived, lower, cambrian, species, known, from, great, basin, california, nevada, arizona. Nephrolenellus is an extinct genus of trilobite fossil marine arthropods of relatively small size sagittal length of cephalon rarely exceeds 11 mm Currently two species are attributed to it Nephrolenellus lived at the end of the Lower Cambrian Species are known from the Great Basin of California Nevada and Arizona with one specimen from Canada 2 NephrolenellusTemporal range Toyonian Upper Olenellus zone 516 513 Ma PreꞒ Ꞓ O S D C P T J K Pg N juvenile Nephrolenellus multinodus 9mm frontal glabellar lobe broken Scientific classification Kingdom Animalia Phylum Arthropoda Class Trilobita Order Redlichiida Suborder Olenellina Superfamily Olenelloidea Family Biceratopsidae Subfamily Biceratopsinae Genus NephrolenellusPalmer amp Repina 1993 Species Nephrolenellus multinodus Palmer in Palmer and Halley 1979 Type synonyms Olenellus multinodus N jasperensis 1 Nephrolenellus geniculatus Palmer 1998 2 Contents 1 Taxonomy 2 Distribution 3 Description 4 ReferencesTaxonomy editN geniculatus may have been a direct descendant of N multinodus 2 Distribution editNephrolenellus multinodus occurs in the late Lower Cambrian of California Toyonian Pyramid Shale Member Carrara Formation Inyo County 35 8 N 116 2 W 3 and of Nevada Toyonian Lincoln County and C Shale Member Pioche Formation Ruin Wash Chief Range 37 8 N 114 6 W 4 Description edit nbsp A drawing of the cephalon of Nephrolenellus geniculatus nbsp A drawing of the cephalon of Nephrolenellus multinodus As with most early trilobites Nephrolenellus has an only thinly calcified exoskeleton Although most of the body is rather flat the frontal lobe L4 of the central area of the cephalon or glabella is raised but not bulbous and does not overlap the border at the front in dorsal view It also has the crescent shaped eye ridges typical for the earliest trilobites As part of the Olenellina suborder Nephrolenellus lacks dorsal sutures Like all other members of the Olenelloidea superfamily the eye ridges spring from the back of the frontal lobe L4 of the glabella Typically for Nephrolenellus the eyeridges are pointing backwards and significantly 45 outwards along the tangent between the base and termination The glabella is strongly hourglass shaped very much constricted at the second pair of side lobes L2 The furrow between the second and third pair of lobes S2 is transverse or gently convex anteriorly S3 is pit like and isolated from furrow defining the glabella or axial furrow The spine at the outer backside of the cephalon is longer than the most backward lobe of the glabella also called occipital ring or L0 and it is based at point the cephalon is at its widest The prothorax consist of thirteen segments and the third segments has enlarged side lobes or pleural lobes that each carry trailing spine at the side that is comparable in length to the entire exoskeleton It lacks the long axial spine where prothorax ends The portion of the thorax where the pleural lobes are reduced or opisthothorax consist of at least 23 segments References edit Lieberman B S 1999 Systematic Revision of the Olenelloidea Trilobita Cambrian PDF Bulletin of the Peabody Museum of Natural History 45 a b c M Webster 2007 Ontogeny and evolution of the early Cambrian trilobite genus Nephrolenellus Olenelloidea Journal of Paleontology 81 6 1168 1193 Bibcode 2007JPal 81 1168W doi 10 1666 06 092 1 S2CID 85652241 E D Fowler 1999 Biostratigraphy of upper Dyeran strata of the Carrara Formation Emigrant Pass Nopah Range California Laurentia 99 V field conference of the Cambrian Stage Subdivision Working Group International Subcomission on Cambrian Stratigraphy pp 46 50 Palmer A R 1998 Terminal Early Cambrian Extinction of the Olenellina Documentation from the Pioche Formation Nevada Journal of Paleontology 72 4 650 672 Bibcode 1998JPal 72 650P doi 10 1017 S0022336000040373 JSTOR 1306693 S2CID 131861504 nbsp This Redlichiida related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Nephrolenellus amp oldid 1193891242, wikipedia, wiki, book, books, library,
