A Paleozoic stem hagfish Myxinikela siroka — revised anatomy and implications for evolution of the living jawless vertebrate lineages

2020 ◽  
Vol 98 (12) ◽  
pp. 850-865
Author(s):  
Tetsuto Miyashita
Keyword(s):  
Soft Tissue ◽  
Fossil Record ◽  
Estuarine System ◽  
Single Specimen ◽  
Calibration Point ◽  
Crown Group ◽  
Total Group ◽  
Posterior Displacement ◽  
Well Differentiated ◽  
Branchial Region

Hagfishes and lampreys comprise cyclostomes, the earliest branching and sole surviving clade of the once diverse assemblage of jawless crown-group vertebrates. Lacking mineralized skeletons, both of the crown cyclostome lineages have notoriously poor fossil record. Particularly in the hagfish total group, †Myxinikela siroka Bardack, 1991 from the Late Carboniferous estuarine system of Illinois (USA) represents the only definitive stem taxon. Previously known from a single specimen, Myxinikela has been reconstructed as a short-bodied form with pigmented eyes but otherwise difficult to distinguish from the living counterpart. With a new, second specimen of Myxinikela reported here, I reevaluate the soft tissue anatomy and formulate diagnosis for the taxon. Myxinikela has a number of general features of cyclostomes, including cartilaginous branchial baskets, separation between the esophageal and the branchial passages, and a well-differentiated midline finfold. In effect, these features give more lamprey-like appearance to this stem hagfish than previously assumed. Myxinikela still has many traits that set modern hagfishes apart from other vertebrates (e.g., nasohypophyseal aperture, large velar cavity, and cardinal heart) and some intermediate conditions of modern hagfishes (e.g., incipient posterior displacement of branchial region). Thus, Myxinikela provides an important calibration point with which to date origins of these characters.

scholarly journals Early fossil record of Euarthropoda and the Cambrian Explosion

2018 ◽  
Vol 115 (21) ◽  
pp. 5323-5331 ◽  
Author(s):  
Allison C. Daley ◽  
Jonathan B. Antcliffe ◽  
Harriet B. Drage ◽  
Stephen Pates
Keyword(s):  
Fossil Record ◽  
Trace Fossils ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Crown Group ◽  
Total Group ◽  
Stem Lineage ◽  
Coherent Picture ◽  
Insight Into ◽  
Phosphate Deposits

Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris) that provide insight into the step-by-step construction of euarthropod morphology, including the exoskeleton, biramous limbs, segmentation, and cephalic structures. Trilobites are crown group euarthropods that appear in the fossil record at 521 Ma, before the stem lineage fossils, implying a ghost lineage that needs to be constrained. These constraints come from the trace fossil record, which show the first evidence for total group Euarthropoda (e.g., Cruziana, Rusophycus) at around 537 Ma. A deep Precambrian root to the euarthropod evolutionary lineage is disproven by a comparison of Ediacaran and Cambrian lagerstätten. BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossiliferous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma). This constrains the appearance of the euarthropod stem lineage to no older than 550 Ma. While each of the major types of fossil evidence (BSTs, trace fossils, and biomineralized preservation) have their limitations and are incomplete in different ways, when taken together they allow a coherent picture to emerge of the origin and subsequent radiation of total group Euarthropoda during the Cambrian.

scholarly journals Diversification dynamics of total-, stem-, and crown-groups are compatible with molecular clock estimates of divergence times

2021 ◽  
Vol 7 (24) ◽  
pp. eabf2257
Author(s):  
Alan J. S. Beavan ◽  
Davide Pisani ◽  
Philip C. J. Donoghue
Keyword(s):  
Time Scales ◽  
Molecular Clock ◽  
Fossil Record ◽  
Divergence Times ◽  
Evolutionary Time ◽  
Crown Group ◽  
Total Group ◽  
Fossil Evidence ◽  
Evolutionary Radiations ◽  
Birth Death

Molecular evolutionary time scales are expected to predate the fossil evidence, but, particularly for major evolutionary radiations, they can imply extremely protracted stem lineages predating the origin of living clades, leading to claims of systematic overestimation of divergence times. We use macroevolutionary birth-death models to describe the range of total-group and crown-group ages expected under constant rates of speciation and extinction. We extend current predictions on origination times for crown- and total-groups, and extinction of stem-groups, demonstrating that there is broad variance in these predictions. Under constant rates of speciation and extinction, we show that the distribution of expected arthropod total-group ages is consistent with molecular clock estimates. The fossil record cannot be read literally, and our results preclude attempts to interpret the antiquity of clades based on the co-occurrence of stem- and crown-representatives.

scholarly journals New mid-Cretaceous cryptic slime mold beetles and the early evolution of Sphindidae (Coleoptera: Cucujoidea)

2021 ◽  
Vol 79 ◽  
pp. 587-597
Author(s):  
Yan-Da Li ◽  
Erik Tihelka ◽  
Zhen-Hua Liu ◽  
Di-Ying Huang ◽  
Chen‑Yang Cai
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Slime Mold ◽  
Early Evolution ◽  
Calibration Point ◽  
Crown Group ◽  
Slime Molds ◽  
The Family ◽  
Group Members

Abstract The cryptic slime mold beetles, Sphindidae, are a moderately diverse cucujoid beetle family, whose members are obligately tied to slime molds throughout their life. The fossil record of sphindid beetles is sparse; stem-sphindids and crown-group members of uncertain systematic placement have been reported from Cretaceous ambers. Here we review the Mesozoic fossil record of Sphindidae and report a new sphindid genus and species, Trematosphindus newtonigen. et sp. nov., from Albian/Cenomanian amber from northern Myanmar (ca. 99 Ma). Trematosphindus is set apart from all other sphindids by the presence of distinct lateral cavities on the anterior pronotal angles. Our phylogenetic analysis identifies Trematosphindus as an early-diverging genus within Sphindidae, sister to the remainder of the family except Protosphindus, or Protosphindus and Odontosphindus. The new fossils provide evidence that basal crown slime mold beetles begun to diversify by the mid-Cretaceous, providing a valuable calibration point for understanding timescale of sphindid co-evolution with slime molds.

New fossil Odonata from the Upper Jurassic of Bavaria with a new fossil calibration point for Zygoptera

2019 ◽  
Vol 2 (6) ◽  
pp. 618-632 ◽  
Author(s):  
GÜNTER BECHLY
Keyword(s):  
New Taxa ◽  
Fossil Record ◽  
Upper Jurassic ◽  
New Taxon ◽  
Calibration Point ◽  
Crown Group ◽  
Fossil Calibration ◽  
Solnhofen Limestone

Three new taxa of odonates are described from the Upper Jurassic Solnhofen limestone from Eichstätt and Painten in Bavaria (Germany), including the first two genuine Zygoptera (Andrephlebia buergeri gen. et sp. nov. in fam. inc. sed. and Jurahemiphlebia haeckeli gen. et sp. nov. in Hemiphlebiidae) and a new taxon of Stenophlebioptera (Reschiostenophlebia koschnyi gen. et sp. nov. in Stenophlebiidae). With an age of about 152 million years, the holotype of Jurahemiphlebia from the Painten locality represents the oldest fossil record and thus a new calibration point for crown group Zygoptera, Lestoidea, and Hemiphlebiidae, and the oldest record for any living odonate family. Furthermore, the first relatively complete specimen of the dragonfly Prohemeroscopus kuehnapfeli (Prohemeroscopidae) is described, which was previously known only from a pair of isolated hind wings. A revised diagnosis is provided for the species and genus.

scholarly journals Femoral sheath lipoma causing venous obstruction syndrome

2010 ◽  
Vol 92 (6) ◽  
pp. e21-e22 ◽  
Author(s):  
Andrew Day ◽  
Paul Thomas
Keyword(s):  
Soft Tissue ◽  
Subcutaneous Tissue ◽  
Venous Obstruction ◽  
Soft Tissue Tumours ◽  
Venous Flow ◽  
Well Differentiated

Lipomas are benign, encapsulated, soft-tissue tumours composed of well-differentiated adipocytes. They arise in the subcutaneous tissue typically on the back, shoulder and neck. Lipomas have been known to cause symptomatic obstruction to venous flow by compression. We report a case of venous obstruction syndrome due to a small lipoma within the femoral sheath.

scholarly journals Retroperitoneal Liposarcoma Presenting as Bilateral Inguinal Hernias

2021 ◽  
Author(s):  
DO Haley S. Lehman ◽  
DO Ryan N. Qasawa ◽  
John J. Lim
Keyword(s):  
Case Report ◽  
Soft Tissue ◽  
Soft Tissue Sarcomas ◽  
Mass Effect ◽  
Potential Space ◽  
Retroperitoneal Liposarcoma ◽  
Median Size ◽  
Inguinal Hernias ◽  
Retroperitoneal Tumors ◽  
Well Differentiated

Abstract Liposarcoma is one of the most common soft tissue sarcomas and has multiple subtypes, including atypical, well-differentiated, and dedifferentiated liposarcoma1. These tumors most commonly occur in the extremities and the retroperitoneum2, and account for 20% of all retroperitoneal tumors3. Retroperitoneal liposarcoma is very rare overall, occurring in 2.5 per one million people4. Patients will present from symptoms of mass effect due to the uncontrolled growth in the large potential space of the retroperitoneum, with its median size being around 30 cm5. The mainstay of treatment for this type of tumor is resection to a negative margin6. This is a case report describing a retroperitoneal liposarcoma presenting with bilateral inguinal hernias containing intraperitoneal fat from mass effect.

Dual-energy X-ray absorptiometry lean soft tissue hydration: independent contributions of intra- and extracellular water

2004 ◽  
Vol 287 (5) ◽  
pp. E842-E847 ◽  
Author(s):  
Marie-Pierre St-Onge ◽  
ZiMian Wang ◽  
Mary Horlick ◽  
Jack Wang ◽  
Steven B. Heymsfield
Keyword(s):  
Soft Tissue ◽  
Water Distribution ◽  
Dual Energy ◽  
Healthy Adults ◽  
Intracellular Water ◽  
Whole Body ◽  
Extracellular Water ◽  
Cross Sectional ◽  
Total Group ◽  
X Ray

Dual-energy X-ray absorptiometry (DEXA) provides a measure of lean soft tissue (LST). LST hydration, often assumed to be constant, is relevant to several aspects of DEXA body composition estimates. The aims of this study were to develop a theoretical model of LST total body water (TBW) content and to examine hydration effects with empirically derived model coefficients and then to experimentally test the model's prediction that, in healthy adults, LST hydration is not constant but varies as a function of extra- and intracellular water distribution (E/I). The initial phase involved TBW/LST model development and application with empirically derived model coefficients. Model predictions were then tested in a cross-sectional study of 215 healthy adults. LST was measured by DEXA, extracellular water (ECW) by NaBr dilution, intracellular water (ICW) by whole body 40K counting, and TBW by 2H2O dilution. TBW estimates, calculated as ECW + ICW, were highly correlated with ( r = 0.97, SEE = 2.1 kg, P < 0.001) and showed no significant bias compared with TBW measured by 2H2O. Model-predicted TBW/LST was almost identical to experimentally derived values (means ± SD) in the total group (0.767 vs. 0.764 ± 0.028). LST hydration was significantly correlated with E/I (total group, r = 0.30, SEE = 0.027, P < 0.001). Although E/I increased with age (men, r = 0.48; women, r = 0.37; both P < 0.001), the association between TBW/LST and age was nonsignificant. Hydration of the DEXA-derived LST compartment is thus not constant but varies predictably with ECW and ICW distribution. This observation has implications for the accuracy of body fat measurements by DEXA and the use of TBW as a means of checking DEXA system calibration.

scholarly journals Well-Differentiated Liposarcoma of The Larynx: A Case Report and Review of Literature

2016 ◽  
Vol 9 (1) ◽  
pp. 85-89
Author(s):  
Svetlana A. Mateva ◽  
Margarita R. Nikolova ◽  
Alexandar V. Valkov ◽  
Margarita R. Nikolova
Keyword(s):  
Case Report ◽  
Soft Tissue ◽  
Soft Tissue Sarcomas ◽  
World Health ◽  
Low Grade ◽  
Review Of Literature ◽  
Grade Malignancy ◽  
Well Differentiated ◽  
Health Organization ◽  
Histologic Types

Summary Liposarcoma is one of the most common soft tissue sarcomas in adults with a relative incidence amongst other sarcomas ranging from 9.8% to 16%. It usually locates in the limbs and retroperitoneum. Primary liposarcomas of the larynx and hypopharynx are rare, comprising less than 20% of all head and neck liposarcomas. According to World Health Organization, these tumors are divided into four histologic types, and well-differentiated liposarcoma is the most common one. It is a tumor of low-grade malignancy that may recur locally, but does not metastasize. We present a case of laryngopharyngeal well- differentiated liposarcoma in an old patient with two previous removals. We also discuss recently published cases with this unusual location of liposarcoma.

scholarly journals Jaw elements in Plumulites bengtsoni confirm that machaeridians are extinct armoured scaleworms

2019 ◽  
Vol 286 (1907) ◽  
pp. 20191247 ◽  
Author(s):  
Luke A. Parry ◽  
Gregory D. Edgecombe ◽  
Dan Sykes ◽  
Jakob Vinther
Keyword(s):  
Phylogenetic Analysis ◽  
Early Evolution ◽  
The Body ◽  
Common Origin ◽  
Discrete Elements ◽  
Crown Group ◽  
Total Group ◽  
Early Ordovician ◽  
Jaw Apparatus ◽  
Competing Hypotheses

Machaeridians are Palaeozoic animals that are dorsally armoured with serialized, imbricating shell plates that cover or enclose the body. Prior to the discovery of an articulated plumulitid machaeridian from the Early Ordovician of Morocco that preserved unambiguous annelid characters (segmental parapodia with chaetae), machaeridians were a palaeontological mystery, having been previously linked to echinoderms, barnacles, tommotiids (putative stem-group brachiopods) or molluscs. Although the annelid affinities of machaeridians are now firmly established, their position within the phylum and relevance for understanding the early evolution of Annelida is less secure, with competing hypotheses placing Machaeridia in the stem or deeply nested within the crown group of annelids. We describe a scleritome of Plumulites bengtsoni from the Fezouata Formation of Morocco that preserves an anterior jaw apparatus consisting of at least two discrete elements that exhibit growth lines. Although jaws have multiple independent origins within the annelid crown group, comparable jaws are present only within Phyllodocida, the clade that contains modern aphroditiforms (scaleworms and relatives). Phylogenetic analysis places a monophyletic Machaeridia within the crown group of Phyllodocida in total-group Aphroditiformia, consistent with a common origin of machaeridian shell plates and scaleworm elytrae. The inclusion of machaeridians in Aphroditiformia truncates the ghost lineage of Phyllodocida by almost a hundred million years.

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