Long bone histology and microanatomy of Placodontia (Diapsida: Sauropterygia)

Placodontia, an enigmatic group of durophagous and in part heavily armoured animals, were members of Sauropterygia, the most diverse and successful group of Mesozoic marine reptiles. Microanatomy and histology of long bones of several armoured and non-armoured Placodontia were studied, covering most of their taxonomic breadth, to elucidate the paleoecology, physiology, and lifestyle of its members. Results reveal an unexpected and not phylogenetically or stratigraphically related disparity of microanatomical and histological features for the group. The non-armoured Paraplacodus and the heavily armoured Psephoderma grew with lamellar-zonal bone tissue type, which is typical for modern sauropsids. In the former, the tissue is nearly avascular surrounding a compacted medullary region, whereas in the latter, the lamellar-zonal bone tissue is vascularized framing a large open medullary cavity and a perimedullary region. Armoured Henodus and Placodontia indet. aff. Cyamodus as well as non-armoured Placodus exhibit a reduced medullary cavity and grew with highly vascularized plexiform to radiating fibro-lamellar bone. Several long bones of Placodontia indet. show circumferential fibro-lamellar bone and can be distinguished into two groups on the basis of microanatomical features. In addition, all bones that grew with fibro-lamellar bone show locally primary spongeous-like architecture and had secondarily widened primary osteons throughout the cortex, resulting in a secondarily spongeous tissue. The highly vascularized fibro-lamellar bone of these Placodontia indicates growth rates comparable to that of open marine ichthyosaurs. Differences in microanatomy and bone histology as expressed by a principal component analysis, thus clearly indicate different paleoecologies, including differences in lifestyle and swimming modes and capabilities in Placodontia. This would have reduced competition in the shallow marine environments of the Tethys and might be a key to their success and diversity. A certain developmental plasticity among the studied placodonts is interpreted as response to different environmental conditions as is obvious from inter- and intraspecific histological variation. Most striking is the difference in life history strategy in armoured Psephoderma and non-armoured Paraplacodus when compared to armoured Henodus, Placodontia indet. aff. Cyamodus, non-armoured Placodus, and Placodontia indet. Bone tissue of Psephoderma and Paraplacodus indicates low growth rates and a low basal metabolic rate, as many modern sauropsids have such as the marine iguana, whereas the others grew with extremely fast growth rates, more typical for birds and mammals, indicating an increased basal metabolic rate.

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Case study of radial fibrolamellar bone tissues in the outer cortex of basal sauropods

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0143 ◽

2020 ◽

Vol 375 (1793) ◽

pp. 20190143 ◽

Cited By ~ 4

Author(s):

Benjamin Jentgen-Ceschino ◽

Koen Stein ◽

Valentin Fischer

Keyword(s):

Bone Tissue ◽

Periosteal Reaction ◽

Bone Histology ◽

Long Bones ◽

Pathological Feature ◽

Bone Surface ◽

Theme Issue ◽

Outer Cortex ◽

Aggressive Form

The histology of sauropod long bones often appears uniform and conservative along their evolutionary tree. One of the main aspects of their bone histology is to exhibit a fibrolamellar complex in the cortex of their long bones. Here, we report another bone tissue, the radial fibrolamellar bone (RFB), in the outer cortex of the humeri of a young adult cf. Isanosaurus (Early to Late Jurassic, Thailand) and an adult Spinophorosaurus nigerensis (Early to Middle Jurassic, Niger) that do not exhibit any pathological feature on the bone surface. Its location within the cortex is unexpected, because RFB is a rapidly deposited bone tissue that would rather be expected early in the ontogeny. A palaeopathological survey was conducted for these sampled specimens. Observed RFB occurrences are regarded as spiculated periosteal reactive bone, which is an aggressive form of periosteal reaction. A ‘hair-on-end’ pattern of neoplasmic origin (resembling a Ewing's sarcoma) is favoured for cf. Isanosaurus , while a sunburst pattern of viral or neoplasmic origin (resembling an avian osteopetrosis or haemangioma) is favoured for Spinophorosaurus . This study highlights the importance of bone histology in assessing the frequency and nature of palaeopathologies. This article is part of the theme issue ‘Vertebrate palaeophysiology’.

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Growth patterns and life-history strategies in Placodontia (Diapsida: Sauropterygia)

Royal Society Open Science ◽

10.1098/rsos.140440 ◽

2015 ◽

Vol 2 (7) ◽

pp. 140440 ◽

Cited By ~ 14

Author(s):

Nicole Klein ◽

James M. Neenan ◽

Torsten M. Scheyer ◽

Eva Maria Griebeler

Keyword(s):

Life History ◽

Bone Tissue ◽

Developmental Plasticity ◽

Growth Models ◽

Age At Onset ◽

Growth Curves ◽

Growth Patterns ◽

Tissue Type ◽

Life History Strategies ◽

Long Bone

Placodontia is a clade of durophagous, near shore marine reptiles from Triassic sediments of modern-day Europe, Middle East and China. Although much is known about their primary anatomy and palaeoecology, relatively little has been published regarding their life history, i.e. ageing, maturation and growth. Here, growth records derived from long bone histological data of placodont individuals are described and modelled to assess placodont growth and life-history strategies. Growth modelling methods are used to confirm traits documented in the growth record (age at onset of sexual maturity, age when asymptotic length was achieved, age at death, maximum longevity) and also to estimate undocumented traits. Based on these growth models, generalized estimates of these traits are established for each taxon. Overall differences in bone tissue types and resulting growth curves indicate different growth patterns and life-history strategies between different taxa of Placodontia. Psephoderma and Paraplacodus grew with lamellar-zonal bone tissue type and show growth patterns as seen in modern reptiles. Placodontia indet. aff. Cyamodus and some Placodontia indet. show a unique combination of fibrolamellar bone tissue regularly stratified by growth marks, a pattern absent in modern sauropsids. The bone tissue type of Placodontia indet. aff. Cyamodus and Placodontia indet. indicates a significantly increased basal metabolic rate when compared with modern reptiles. Double lines of arrested growth, non-annual rest lines in annuli, and subcycles that stratify zones suggest high dependence of placodont growth on endogenous and exogenous factors. Histological and modelled differences within taxa point to high individual developmental plasticity but sexual dimorphism in growth patterns and the presence of different taxa in the sample cannot be ruled out.

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Bone histology of Azendohsaurus laaroussii: Implications for the evolution of thermometabolism in Archosauromorpha

Paleobiology ◽

10.1017/pab.2019.13 ◽

2019 ◽

Vol 45 (02) ◽

pp. 317-330 ◽

Cited By ~ 8

Author(s):

Jorge Cubo ◽

Nour-Eddine Jalil

Keyword(s):

Metabolic Rate ◽

Growth Rates ◽

Resting Metabolic Rate ◽

High Growth ◽

Sister Group ◽

Bone Histology ◽

Character State ◽

Last Common Ancestor ◽

Metabolic Rates ◽

Good Proxy

AbstractThis paper is aimed at constraining the phylogenetic frame of the acquisition of endothermy by Archosauromorpha. We analyzed the bone histology of Azendohsaurus laaroussii. Stylopodial and zeugopodial bones show three tissue types: (1) avascular lamellar zonal bone formed at low growth rates; (2) a scaffold of parallel-fibered bone containing either small primary osteons or simple vascular canals; and (3) fibrolamellar bone formed at high growth rates. We used quantitative histology to infer the thermometabolic regime of this taxon. We define endothermy as the presence of any mechanism of nonshivering thermogenesis that increases both body temperature and resting metabolic rate. Thus, estimating the resting metabolic rate of an extinct organism may be a good proxy to infer its thermometabolic regime (endothermy vs. ectothermy). High resting metabolic rates have been shown to be primitive for the clade Prolacerta–Archosauriformes. Therefore, we inferred the resting metabolic rates of A. laaroussii, a sister group of this clade, and of 14 extinct related taxa, using phylogenetic eigenvector maps. All the inferences obtained are included in the range of variation of resting metabolic rates measured in mammals and birds, so we can reasonably assume that all these taxa (including Azendohsaurus) were endotherms. A parsimony optimization of the presence of endothermy on a phylogenetic tree of tetrapods shows that this derived character state was acquired by the last common ancestor of the clade Azendohsaurus–Archosauriformes and that there is a reversion in Crocodylia.

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Can secondary osteons be used as ontogenetic indicators in sauropods? Extending the histological ontogenetic stages into senescence

Paleobiology ◽

10.1017/pab.2016.47 ◽

2017 ◽

Vol 43 (2) ◽

pp. 321-342 ◽

Cited By ~ 9

Author(s):

Jessica Mitchell ◽

P. Martin Sander ◽

Koen Stein

Keyword(s):

Growth Rates ◽

Bone Development ◽

High Growth ◽

Bone Histology ◽

Long Bones ◽

Asymptotic Size ◽

Ontogenetic Stages ◽

Annual Growth Rings ◽

Insight Into ◽

Secondary Osteons

AbstractSauropod bone histology has provided a great deal of insight into the life history of these enormous animals. However, because of high growth rates, annual growth rings are not common in sauropod long bones, so directly measuring growth rates and determining sexual maturity require alternative measures. Histological ontogenetic stages (HOS) have been established to describe the changes in bone histology through development for basal Macronaria and Diplodocoidea, and subsequently for Titanosauria. Despite this, the current HOS model is not able to discriminate bone tissues in late ontogeny, when sauropods had reached asymptotic size and continued to live into senescence but their long bones became extensively remodeled by secondary osteons and all primary bone was destroyed. Here we establish remodeling stages (RS) to characterize the Haversian bone development through ontogeny in eight sauropod taxa (Apatosaurinae, Giraffatitan brancai, Camarasaurus spp., Dicraeosaurus spp., Ampelosaurus atacis, Phuwiangosaurus sirindhornae, Magyarosaurus dacus, and Alamosaurus sanjuanensis) and find significant correlation of RS with corresponding femur length (CFL) for the studied taxa, with the exception of Dicraeosaurus and Magyarosaurus. Remodeling stages are based on the maximum number of observable generations of crosscutting osteons from the innermost, mid-, and outermost part of the cortex. The correlation with CFL indicates that secondary osteons present an ontogenetic signal that could extend the histological ontogenetic stages. Remodeling stages also provide additional insight into the changes in histology through ontogeny for Sauropoda. This method has the potential to be used in other taxa, such as thyreophorans and many ornithischians, that develop Haversian tissue through development.

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Osteohistology of the hadrosauroid (Dinosauria: Ornithopoda) from Labirinta cave, Bulgaria: An example of insular dwarfism or simply young giant?

10.31233/osf.io/b2en4 ◽

2018 ◽

Author(s):

Vladimir Georgiev Nikolov

Keyword(s):

Bone Tissue ◽

Bone Remodeling ◽

Growth Rates ◽

Fundamental System ◽

Lamellar Bone ◽

Mature Animal ◽

Thin Sections ◽

Tissue Matrix ◽

Secondary Osteons ◽

Upper Maastrichtian

The hadrosauroid remains from Kajlâka Formation (Upper Maastrichtian) limestones of the Labirinta Cave, NW Bulgaria, are most interesting for their small size but without paleohistological data it was not possible to affirm whether they belong to young individual/s or to small-sized mature animal/s. To elucidate their histology and ontogenetic state, 6 associated cortical fragments and one partial diaphysis were sectioned and studied. Thin-sections reveal cortex build of highly vascularized tissues of the woven-parallel complex. Vascularization patterns are somewhat intermediate between those of derived hadrosauroids and non-hadrosauroid ornithopods, yet characterized by thick sequences of laminar bone. Bone tissue matrix consists largely of parallel-fibered or lamellar bone tissue. Cortical tissues are affected by processes of secondary remodeling that locally results in dense Haversian tissue reaching the subperiosteal cortex. No growth marks or external fundamental system are observed in any of the specimens. The transition from bone tissues with predominantly longitudinally oriented osteons to true laminar bone, the thickness of the latter, the extensive secondary bone remodeling and Haversian tissue with at least 3 generations of secondary osteons, as well as the presence of endosteal bone in one of studied specimens all suggest that the material pertains to animal/s at a late sub-adult ontogenetic stage. The high presence of parallel-fibered and lamellar tissues in the cortex indicates significantly slower growth rates in comparison with similarly sized but ontogenetically younger derived hadrosauroids. The osteohistology of the Bulgarian hadrosauroid reveals yet another example of dinosaurian insular dwarfism in latest Cretaceous European archipelago.

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Development of new predictive equations for basal metabolic rate in Iranian healthy adults: negligible effect of sex

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000669 ◽

2020 ◽

pp. 1-10

Author(s):

Bahareh Nikooyeh ◽

Nastaran Shariatzadeh ◽

Ali Kalayi ◽

Maliheh Zahedirad ◽

Tirang R. Neyestani

Keyword(s):

Metabolic Rate ◽

Thyroid Function ◽

Basal Metabolic Rate ◽

Age Groups ◽

Thyroid Function Tests ◽

Anthropometric Measures ◽

Predictive Equations ◽

Normal Thyroid Function ◽

Asian People ◽

Predictive Formulas

Abstract. Some studies have reported inaccuracy of predicting basal metabolic rate (BMR) by using common equations for Asian people. Thus, this study was undertaken to develop new predictive equations for the Iranian community and also to compare their accuracy with the commonly used formulas. Anthropometric measures and thyroid function were evaluated for 267 healthy subjects (18–60 y). Indirect calorimetry (InCal) was performed only for those participants with normal thyroid function tests (n = 252). Comparison of predicted RMR (both kcal/d and kcal.kg.wt−1.d−1) using current predictive formulas and measured RMR revealed that Harris-Benedict and FAO/WHO/UNU significantly over-estimated and Mifflin-St. Jeor significantly under-estimated RMR as compared to InCal measurements. In stepwise regression analysis for developing new equations, the highest r2 (=0.89) was from a model comprising sex, height and weight. However, further analyses revealed that unlike the subjects under 30 y, the association between age and the measured RMR in subjects 30 y and plus was negative (r = −0.241, p = 0.001). As a result, two separate equations were developed for these two age groups. Over 80 percent of variations were covered by the new equations. In conclusion, there were statistical significant under- and over-estimation of RMR using common predictive equations in our subjects. Using the new equations, the accuracy of the calculated RMR increased remarkably.

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COMBINATION OF POTASSIUM PERCHLORATE AND PROPYLTHIOURACIL IN THE TREATMENT OF THYROTOXICOSIS

Acta Endocrinologica ◽

10.1530/acta.0.0570565 ◽

1968 ◽

Vol 57 (4) ◽

pp. 565-577 ◽

Cited By ~ 4

Author(s):

K. E. Røkke ◽

J. H. Vogt

Keyword(s):

Drug Therapy ◽

Side Effects ◽

Metabolic Rate ◽

Total Cholesterol ◽

Basal Metabolic Rate ◽

Combined Therapy ◽

Combined Treatment ◽

Control Measures ◽

Potassium Perchlorate ◽

Plasma Total Cholesterol

ABSTRACT A report is given on 95 thyrotoxic patients treated with a combination of 400 mg propylthiouracil and 400 mg of potassium perchlorate. Perchlorate was stopped when a marked remission of symptoms was obtained, on an average after less than 7 weeks. Euthyroidism was found on an average after 7.2 weeks. The basal metabolic rate, PBI, plasma total cholesterol and weight showed a fairly rapid normalization. Thirteen of the 95 patients were given radio-iodine therapy shortly before drug therapy was started. The remaining 82 cases were grouped together with the 23 cases previously reported. Of the total of 105 cases, 96 became euthyroid on combined therapy. For the frequency of side-effects, the thirteen cases mentioned above were included, giving a total of 118 cases. Eight cases showed an increase in goitre size and 15 cases had other side-effects, of which three were granulocytopenia due to propylthiouracil. The possibility of a higher frequency of mainly minor side-effects on combined therapy has to be balanced against the seemingly rapid and reliable therapeutic effect. Combined treatment, perhaps with even smaller doses than reported here, can be recommended in selected cases of thyrotoxicosis where a shortening of the thyrotoxic state seems of importance, or possibly where difficulties due to iodine exposure may be anticipated, provided adequate control measures are taken.

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