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Acinocricus stichus (Conway-Morris & Robison 1988)
Acinocricus is a genus of extinct worm belonging to the group Lobopodia and known from the middle Cambrian Spence Shale of Utah, United States. As a monotypic genus, it has one species Acinocricus stichus. The only lobopodian discovered from the Spence Shale, it was described by Simon Conway Morris and Richard A. Robison in 1988.Owing to the original fragmentary fossils discovered since 1982, it was initially classified as an alga, but later realised to be an animal belonging to Cambrian fauna. The first specimen of Acinocricus was discovered by American palaeontologist Lloyd Gunther in 1982 from the Spence Shale in Miners Hollow, Wellsville Mountains, Utah. It was embedded in hardened mud and was incomplete with some of its body part missing. More than a dozen fragmentary fossils were later recovered from the same site and the surrounding areas. Simon Conway Morris of the University of Cambridge and Richard A. Robison of the University of Kansas jointly published the systematic description and scientific name in 1988. The generic name is derived from two Greek words, akaina, meaning thorn or spine, and krikos, meaning ring or circle, for the circular spines on its body; the specific name stichos means row or line, referring to the arrangement of the spines.[1] Morris and Robison made an erroneous classification by assigning it as an alga (in the phylum Chlorophyta) as they were convinced that it had no particular resemblance to any known animal fossils (medusoid) known at the time. The correct identification as an animal came only after a series of discoveries of Cambrian fossils (Maotianshan Shales) in Chengjian, China. A variety of lobopods were discovered in the early 1990s that showed important shared features with Acinocricus.[4][5][6] Comparison of the Chengjian lobopods and Acinocricus revealed their similarities.[3] In 1998, Jun-yuan Chen (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences) and Lars Ramsköld (Uppsala University, Sweden) made assessment of all available Cambrian lobopod fossils and came to the conclusion that Acinocricus belongs to Lobopodia.
斯彭斯页岩 2018 苗岭年：五六安
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Amecephalus jamisoni (Robison & Babcock 2011)
Diagnosis.—Amecephalus with long, prominent medial spines on occipital ring and thoracic segments 4 to 12, and variably present on thoracic segments 1 to 3. Glabella moderately tapered, S1 and S2 well developed, S3 and S4 weak. Anterior branches of facial suture strongly divergent. Genal spines moderately long. Thorax having as many as 17 segments, with falcate pleural tips progressively lengthening rearward on anterior thorax and progressively shortening rearward on posterior thorax. Pygidium micropygous, alate with posterior median notch. Etymology.—After Paul Jamison, who collected and prepared the holotype. He also collected and generously donated other specimens used in this study. Types.—Holotype, UU 10051.60 Discussion.—Amecephalus jamisoni differs from all described species of Amecephalus by the presence of an occipital spine and a medial axial spine on most thoracic segments. Its pygidium is known from an unnamed Spence Shale specimen illustrated on the Internet (Marshall, 2011). Most known specimens of A. jamisoni are preserved with the micropygous pygidium and some segments of the posterior thorax projecting downward into the matrix, or tucked under the dorsal surface (see especially Figs. 15.1–15.2). This manner of preservation is interpreted as taphonomic in origin and related to loose flopping of the pygidium as the specimen was carried in a current prior to burial. Occurrence.—Amecephalus jamisoni is rare in the middle part of the Spence Shale at Wellsville Mountain.
Spence Shale Miaolingian: Wuliuan USA
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Asaphiscus wheeleri (Meek, 1873)
Distribution - A. wheeleri occurs in the Middle Cambrian of the United States (Delamaran, Lower Wheeler Shale, Millard County, Utah, 40.0°N, 113.0°W; and Menevian, Wheeler Formation, House Range, Utah, 39.2° N, 113.3° W). Description - Asaphiscus are average size trilobites of (up to 8 centimetres or 3.1 inches) with a rather flat calcified dorsal exoskeleton of inverted egg-shaped outline, about 1½× longer than wide, with the widest point near the back of the headshield (or cephalon). The cephalon is about 40% of the body length, is semi-circular in shape, has wide rounded genal angles, and a well defined border of about ⅛× the length of the cephalon. The central raised area of the cephalon (or glabella is conical in outline with a wide rounded front and is separated from the border by a preglabellar field of about ⅛× the length of the cephalon, and has 3 sets of furrows that may be clear or inconspicuous. The articulated middle part of the body (or thorax) has 7-11 segments (9 in A. wheeleri), with rounded tips. The tailshield (or pygidium) is about 30% of the body length, is semi-circular in shape, with a wide flat border, and an entire margin. A Chinese trilobite Tenistion typicalis was used for scale.
Wheeler Shale Miaolingian USA
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Beckwithia typa (Resser, 1931)
This specimen is a rare example of the aglaspid Beckwithia. Aglaspids resemble the modern-day horseshoe crabs, and contain as the most famous member the Beckwithia typa shown here, a monsterous creature reaching up to some 20 cm in overall length that is thought to have Beckwithia was named after Frank Beckwith, editor and publisher of the Millard County Chronicle of Delta, Utah in the early to middle 1900s, a man with a passion for trilobites. Aglaspids are thought by some scientists to have made the The aglaspidids survived into the Early Ordovician but died out by the end of the period. It has been proposed that they are related to the ancestors of horseshoe crabs and arachnids.
Weeks Upper Middle Cambrian, Cenomanian Stage USA
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Bundenbachochaeta eschenbachensis (Bartels and Blind, 1995)
Diagnosis. Body elongate, oval; 15 to more than 20 parapodia-bearing segments – notopodia and neuropodia differ in the length and number of chaetae (c. 40 and c. 10, respectively). Acicula stout. Prostomium rounded with a pair of short stout appendages. (After Bartels and Blind 1995.) Geological horizons and locality. Eschenbach Member (holotype) and overlying Wingertshell Member (additional specimens) of the Kaub Formation, Obereschenbach Quarry, Bundenbach. Holotype. DBM:HS 717 Description. All specimens are somewhat flattened in parallel aspect. The worm is bilaterally symmetrical and elongate, tapering both anteriorly and posteriorly from a maximum width at about the mid-length, so it is also symmetrical about this point. The four complete specimens are 19 mm long (2 mm wide to the base of the parapodia, 11% of length), 46 mm long (Text-fig. 2C, NM:PWL 2002/222-LS, 7 mm wide, 15% of length), 48 mm long (Text-fig. 1, DBM:HS 717: 8 mm wide, 17% of length), and c. 100 mm long (Text-fig. 2A, B, DBM:HS 736: 23 mm wide, 23% of length). Thus, the width increases relative to length in larger individuals. The holotype (Text-fig. 1; Bartels and Blind 1995) is the best-preserved specimen. The side of the worm exposed cannot be determined with confidence, but it is assumed to be the ventral (and left and right are designated accordingly below). The anterior part of the head is heavily pyritized (as it is in NM:PWL 2002/222-LS, Text-fig. 2C). The structure is not clear, but appears to show traces of two appendages, perhaps palps or antennae; there is no evidence of jaws. The trunk bears c. 20 pairs of parapodia. Those on the right appear to be offset slightly posteriorly (Text-fig. 1C). The parapodia are clearly biramous as evidenced by well-preserved examples anterior of the mid-length on the right side and more posteriorly on the left (Text-fig. 1). The ventral ramus of the parapodia (neuropodium) bears longer more robust chaetae; c. 10 are evident, which are near parallel. They are <10% of the total length of the body. The dorsal ramus (notopodium) bears more delicate chaetae, c. 40 in number, which diverge strongly and are attached over a wider distance. They appear shorter than the chaetae of the ventral ramus in the anterior left parapodia (the difference perhaps exaggerated by preparation) but are more similar in length in the posterior right. The X-radiograph shows strongly pyritized linear structures, particularly on the left side, which extend beyond the proximal part of the parapodia (Text-fig. 1B). At least two per parapodium are evident in some cases. These structures are interpreted as aciculae (Text-fig. 1C). Both chaetae and aciculae are fragmented along their length (Text-fig. 1C), but this is a taphonomic artefact reflecting the nature of pyritization. The trunk terminates in a bifid structure (which does not appear to be made up of parapodia) which may represent a pygidium. A linear structure about the mid-length may represent part of the gut trace (Text-fig. 1A, C). The largest specimen, DBM:HS 736, is assumed to afford a dorsal view (Text-fig. 2A, B). It preserves evidence of 17 pairs of parapodia (there were presumably more), solely as the pyritized remains of the chaetae. The ramus bearing the large number of more slender chaetae is preserved uppermost. The soft tissues of the head and trunk have been lost, presumably through decay. The central area preserves a network of pyritized burrows, some of them revealed in the X-radiograph (Text-fig. 2B), which extend beyond the posterior of the trunk, perhaps representing the activities of a scavenger. The smallest specimen, DBM:HS 597 (Text-fig. 2D), shows evidence of c. 15 pairs of parapodia and presumably represents a juvenile. Only the notopodia appear to be preserved. The nature of the linear structures flanking the trunk axis is unknown, but they may represent longitudinal muscle bands. There are structures at the anterior that are difficult to interpret and might represent jaws or other head appendages.
洪斯吕克板岩 Lower Emsian 德国
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Burlingia halgedahlae (Robison and Babcock, 2011)
Diagnosis—Exoskeleton generally oval in outline, width greatest along anterior thorax, medial posterior margin weakly indented. Cephalon subtriangular, lacking dorsal furrows. Anterior sections of facial suture straight, moderately divergent; posterior sections weakly curved, diverging laterally and slightly forward. Site of effaced occipital ring having small median node. Thorax containing as many as 15 segments, axis widest along midlength. Anterior border of thoracic pleurae raised to form low, narrow ridge. Pygidium narrowly rectangular. Etymology.—After Professor Susan L. Halgedahl, University of Utah, for contributions to knowledge of Cambrian fossils, stratigraphy and depositional environments in Utah. Holotype.—Exoskeleton, UU 10051.55 Discussion.—Burlingia halgedahlae most closely resembles B. hectori Walcott, 1908, from the Stephen Formation of British Columbia. and B. jagoi Whittington, 1994, from the Alum Shale of Sweden and Norway. It is similar to B. hectori in general outlines of the exoskeleton and thoracic axis but has a more triangular cephalon, one more thoracic segment, and a shallower medial indentation of the rear skeletal margin. It is similar to B. jagoi in having a subtriangular cephalon but differs in outline of the raised axial lobe, in having one more thoracic segment, and a deeper and wider indentation of the rear skeletal margin. Burlingia halgedahlae appears to differ from all other species of Burlingia by its greater effacement of dorsal furrows, but that feature may have a taphonomic rather than genetic origin. Occurrence.—Burlingia halgedahlae is rare in the middle part of the Marjum Formation, mid-Bolaspidella Zone, at localities 347 and 716 in the House Range.
Marjum Formation Miaolingian USA
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Cedaria minor (Walcott, 1916)
This trilobite is a member of the family Cedariidae known as Cedaria minor. Cedaria is a small, rather flat trilobite with an oval outline, a headshield and tail shield of approximately the same size, 7 articulating segments in the middle part of the body and spines at the back edges of the head shield that reach halflength of the body. Cedaria lived during the early part of the Upper Cambrian (Dresbachian), and is especially abundant in the Weeks Formation.
Weeks Upper Middle Cambrian, Cenomanian Stage USA
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Cedarina schachti n. sp.
Diagnosis Frontal area and preglabellar field long; anterior border evenly anteriorly arcuate; anterior sections of facial suture strongly anteriorly divergent; palpebral lobes large; pygidium relatively narrow and long. Etymology The species is named in honour of Robert Schacht, who collected and donated the holotype and one of the paratype specimens. source: The Marjuman trilobite Cedarina Lochman: thoracic morphology, systematics, and new species from western Utah and eastern Nevada, USA The thorax of C. schachti has ten segments. The segments have a simple morphology (Fig. 5), featuring a well impressed pleural furrow with a transverse course and distal pleural regions that are tapered into blunt, posteriorly directed pleural spines. The eighth segment bears a long median axial spine. None of the other segments bear any axial nodes or spines. This morphology is all but identical to that seen in the articulated "richardsonellines" cited above. The only difference is that the remopleuridids have two additional thoracic segments posterior to the spine-bearing eighth.
Weeks Upper Middle Cambrian, Cenomanian Stage USA
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Chotecops ferdinandi (Kayser, 1880)
Chot = spouse, consort A ventral specimen with incredible preservation of hypostome, appendages and setae. Chotecops are the most abundant arthropod of the Hunsruck Slate.
Hunsrück Slates 2019 408–400 Mya old
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Deiracephalus aster (Walcott, 1916)
Species of Deiracephalus Resser, 1935, are rare elements in most Guzhangian (upper Marjuman) trilobite faunas of Laurentian North America, and are characterized by striking cephalic spinosity that includes very long genal and occipital or preoccipital glabellar spines. Almost all previous reports of the genus have assigned sclerites to two species, Deiracephalus aster (Walcott, 1916) and Deiracephalus unicornis Palmer, 1962. They usually range up to at least 20mm in length, has a large occipital spine and a medial spine of siilar size on each of 10 thoracic segements. Large, outwardly and backwardly directed genal spines are unusual in arsing from just inside the cephalic border rather than from the outer border surface, as in most polymerid trilobites.
Weeks Upper Middle Cambrian, Cenomanian Stage USA
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Duslia insignis Jahn, 1893
Originally described by Jahn (1983) as a chitnoid mollusc. It was recognized as an arthropod by Pilsbry (1900) and Fritsch (1908). It also shows some morphological analogies with Cheloniellon, Pseudoarthron and Triopus. Duslia inhabited a nearshore shallow marine environment and was probably a benthic animal which lived buried in sandy substrate near the sediment-water interface.
Letna Formation 2020 Late Ordovician
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Elrathia kingi (Meek, 1870)
Elrathia is a genus of ptychopariid trilobite species that lived during the Middle Cambrian of Utah, and possibly British Columbia. E. kingii is one of the most common trilobite fossils in the USA locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. E. kingii has been considered the most recognizable trilobite. Commercial quarries extract E. kingii in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career. 1950 specimens of Elrathia are known from the Greater Phyllopod bed, where they comprise 3.7% of the community. Etymology - Even though the generic name Elrathia was first published in the combination E. kingii, a species from the House Range, Utah, the name, itself, is derived from Elrath, Cherokee County, Alabama. Description - E. kingii is a medium-sized trilobite with a smooth sub-ovate carapace that is tapered towards the rear. Thorax is usually 13 segments. Pygidium has four axial rings and a long terminal piece. Posterior margin of the pygidium has a long broad medial notch. In contrast, E. marjum usually has 12 segments, 5 axial rings, lacks a notched posterior margin and possess incipient antero-lateral spines. The British Columbian species, E. permulta, is much smaller, averaging about only 20 millimeters, and has up to thoracic 14 segments. Because E. permulta lacks several diagnostic features of the genus it may even represent a distinct genus. Synonyms - Elrathia is variously known as Elrathina, which is a separate genus sometimes considered to be a synonym of Ptychoparella. The species E. kingii is often erroneously called E. kingi (with one i).
Wheeler Shale Miaolingian USA
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Emeraldella brocki (Walcott, 1912)
Emeraldella is a genus of arthropod known from the Middle Cambrian of North America. The type species E. brocki was described in 1912 from the Burgess Shale.21 specimens of Emeraldella are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community.[2] A re-study on the species was done in 2012.A second species E. brutoni is known from the Wheeler Shale, which was described in 2011.An additional specimen of E. brutoni was described in 2019, which revealed more of the anatomy.
Wheeler Shale Miaolingian USA
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Furca bohemica Fritsch, 1908
The enigmatic marrellomorph arthropod Furca bohemica from the Upper Ordovician Letná Formation, is redescribed. Based on existing museum specimens and new material collected from the southern slope of Ostrý Hill (Beroun, Czech Republic), the morphology and taphonomy of F. bohemica is reappraised and expanded to produce a new anatomical interpretation. The previously distinct taxa F. pilosa and Furca sp., are synonymised with F. bohemica, the latter being represented by a tapho−series in which decay has obscured some of the diagnostic features. A cladistic analysis indicates close affinities between F. bohemica and the Hunsrück Slate marrellomorph Mimetaster hexagonalis, together forming the Family Mimetasteridae, contrary to previous models for marrellomorph internal relationships. As with other representatives of the group, the overall anatomy of F. bohemica is consistent with a benthic, or possibly nektobenthic, mode of life. The depositional setting of the Letná Formation indicates that F. bohemica inhabited a shallow marine environment, distinguishing it palaeoecologically from all other known marrellomorphs, which have been reported from the continental shelf.
Letna Formation 2018 Late Ordovician
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Genevievella granulata (Walcott, 1916)
Genevievella is a genus of trilobites with a short inverted egg-shaped outline, a wide headshield, small eyes, and long genal spines. The backrim of the headshield is inflated and overhangs the first of the 9 thorax segments. The 8th thorax segment from the front bears a backward directed spine that reaches beyond the back end of the exoskeleton. It has an almost oval tailshield with 5 pairs of pleural furrows. It lived during the Upper Cambrian in what are today Canada and the United States.
Weeks Upper Middle Cambrian, Cenomanian Stage USA
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