scholarly journals Major cranial changes during Triceratops ontogeny

2006 ◽  
Vol 273 (1602) ◽  
pp. 2757-2761 ◽  
Author(s):  
John R Horner ◽  
Mark B Goodwin
Keyword(s):  
Older Adults ◽  
Posterior Margin ◽  
Sexual Maturity ◽  
Shape Function ◽  
Early Ontogeny ◽  
Foramen Magnum ◽  
Growth Stages ◽  
Growth Series ◽  
Visual Identity ◽  
Suture Fusion

This is the first cranial ontogenetic assessment of Triceratops , the well-known Late Cretaceous dinosaur distinguished by three horns and a massive parietal–squamosal frill. Our analysis is based on a growth series of 10 skulls, ranging from a 38 cm long baby skull to about 2 m long adult skulls. Four growth stages correspond to a suite of ontogenetic characters expressed in the postorbital horns, frill, nasal, epinasal horn and epoccipitals. Postorbital horns are straight stubs in early ontogeny, curve posteriorly in juveniles, straighten in subadults and recurve anteriorly in adults. The posterior margin of the baby frill is deeply scalloped. In early juveniles, the frill margin becomes ornamented by 17–19 delta-shaped epoccipitals. Epoccipitals are dorsoventrally compressed in subadults, strongly compressed and elongated in adults and ultimately merge onto the posterior frill margin in older adults. Ontogenetic trends within and between growth stages include: posterior frill margin transitions from scalloped to wavy and smooth; progressive exclusion of the supraoccipital from the foramen magnum; internal hollowing at the base of the postorbital horns; closure of the midline nasal suture; fusion of the epinasal onto the nasals; and epinasal expansion into a morphologically variable nasal horn. We hypothesize that the changes in horn orientation and epoccipital shape function to allow visual identity of juveniles, and signal their attainment of sexual maturity.

Integrated analysis of sexual maturation through successive growth instars in the spider crab Leurocyclus tuberculosus (Decapoda: Majoidea)

2017 ◽  
Vol 95 (7) ◽  
pp. 473-483 ◽  
Author(s):  
Ximena González-Pisani ◽  
Pedro J. Barón ◽  
Laura S. López Greco
Keyword(s):  
Sexual Maturation ◽  
Sexual Maturity ◽  
Carapace Width ◽  
Integrated Analysis ◽  
Growth Stages ◽  
Spider Crab ◽  
Size At Maturity ◽  
Frequency Distributions ◽  
The Right ◽  
Sexually Mature

An integrative analysis of sexual maturity associated with growth was developed for the spider crab Leurocyclus tuberculosus (H. Milne Edwards and Lucas, 1842). Sexual maturity was characterized based on gonadal, morphological, morphometric, and functional sexual maturity. Progress in sexual maturation was described through 13 growth stages (instars) detected by the examination of size (carapace width) frequency distributions. Mature females displayed mature ovaries, developed vaginae, open gonopores, allometric changes in the abdomen, and ovigerous stage in the transition from instar IX to instar X. Sexually mature males presented spermatophores in the distal vasa deferentia and allometric changes in several measurements of the right chela in the transition from instar X to instar XI. However, two prepubertal phases were recognized in both sexes separated from each other by a prepubertal critical molt. Preceding the second critical molt, gonopores were sealed and vasa deferentia showed no spermatophores, and therefore neither sex was able to mate. The integrated analysis of size at maturity and size frequency distributions showed that in both sexes molt to gonadal, morphological, morphometric, and functional sexual maturity occurred in advance of the terminal molt, in contrast with patterns observed in other Majoidea.

A conch with a collar: early ontogeny of the enigmatic fossil bivalveMyoconcha

2012 ◽  
Vol 86 (4) ◽  
pp. 652-658 ◽  
Author(s):  
Andrzej Kaim ◽  
Simon Schneider
Keyword(s):  
Parental Care ◽  
Middle Jurassic ◽  
Early Ontogeny ◽  
Growth Stages ◽  
Juvenile Growth ◽  
Large Size ◽  
Lamellar Layer ◽  
First Time ◽  
New Discovery

Larval and juvenile growth stages of myoconchid bivalves (family Kalenteridae) are illustrated and described for the first time. Excellently preserved shells ofMyoconcha crassaJ. Sowerby, 1824 from the middle Bathonian (Middle Jurassic) clay/silt deposits of southern Poland reveal that the prodissoconch in this taxon is large (exceeding 350 µm in length) and characterized by a prominent, collar-like structure arising from the demarcation to the dissoconch. Similar prodissoconch morphology has not been described previously in any other bivalve genus. The large size and absence of a prodissoconch II strongly suggest a non-planktotrophic development of the larvae, indicating either simple lecithotrophy or long-term brooding and parental care for the larvae in this species. Consequently, the new discovery constitutes the earliest well-documented record of non-planktotrophic development in the Bivalvia. The shell ofMyoconcha crassais composed of an outer cross-lamellar layer and an inner complex cross-lamellar layer. This composition suggests that the Kalenteridae may be included in the Carditida rather than the Palaeoheterodonta or Anomalodesmata. The genusPseudomyoconchaRossi Ronchetti and Allasinaz, 1966 is rejected herein and considered as a junior synonym ofMyoconchaJ. Sowerby, 1824.

Cervical myelopathy due to ossification of the posterior longitudinal longitudinal ligament

1972 ◽  
Vol 37 (6) ◽  
pp. 653-660 ◽  
Author(s):  
Chikao Nagashima
Keyword(s):  
Cervical Myelopathy ◽  
Posterior Margin ◽  
Posterior Longitudinal Ligament ◽  
Foramen Magnum ◽  
Primary Lesion ◽  
Foramen Magnum Decompression ◽  
Decompressive Laminectomy ◽  
Content Type ◽  
Longitudinal Strip ◽  
Fine Print

✓ Ten patients who had cervical myelopathy due to ossification of the posterior longitudinal ligament of the cervical spine are described. This disease is characterized by an abnormal longitudinal strip of ossified ligamentous tissue along the posterior margin of vertebrae from C-3 to C-6; the primary lesion appears to be a degeneration of the intervertebral disc. This distinct clinical, radiological, and pathological entity should be included in the differential diagnosis of cervical myelopathy. All 10 patients were treated by extensive decompressive laminectomy and multiple bilateral facetectomies, with or without foramen magnum decompression. The results were favorable, and postoperative myelography demonstrated dorsal migration of the entire dural contents.

Longbone histology of the Tendaguru sauropods: implications for growth and biology

Paleobiology ◽  
2000 ◽  
Vol 26 (3) ◽  
pp. 466-488 ◽  
Author(s):  
P. Martin Sander
Keyword(s):  
Bone Tissue ◽  
Growth Pattern ◽  
Sexual Maturity ◽  
Sampling Technique ◽  
Maximum Size ◽  
Upper Jurassic ◽  
Growth Line ◽  
Fossil Bone ◽  
Growth Series ◽  
Size At Sexual Maturity

A new sampling technique for fossil bone (coring with a 5/8″ bit) was used to sample longbones of all four sauropod genera from the Upper Jurassic Tendaguru beds of Tanzania for paleohistological study. Brachiosaurus and Barosaurus are represented by growth series of humeri and femora, while Dicraeosaurus could be sampled in fewer specimens and only one bone of Janenschia was available. Although all samples are dominated by fibrolamellar bone tissue, taxa can be distinguished by the degree and nature of bone remodeling and the presence and spacing of a peculiar kind of growth line (here termed “polish lines”). In addition, Barosaurus bone revealed two types of histology, tentatively interpreted as sexual morphs. The Tendaguru sauropods show a common growth pattern in which growth is determinate but sexual maturity is achieved well before maximum size is reached. For Brachiosaurus and Barosaurus, size at sexual maturity can be estimated and was reached at about 40% and 70% maximum size, respectively. Quantification of growth is possible in Janenschia using polish lines: the specimen studied reached sexual maturity at ≥11 years, attained maximum size at ≥26 years, and died at ≥38 years.

scholarly journals Ultrasonographic Examination and Measurements of Testes, Epididymis and Accessory Glands at Different Growth Stages of Chios Rams

2021 ◽  
Author(s):  
Ahmed Ali ◽  
Abdel-Razek Kh. Abdel-razek ◽  
Salem Fahmy
Keyword(s):  
Sexual Maturity ◽  
Tunica Albuginea ◽  
Growth Stages ◽  
Ultrasonographic Examination ◽  
Maximum Thickness ◽  
Accessory Glands ◽  
Scrotal Circumference ◽  
Group A ◽  
Group B ◽  
Different Growth Stages

Background: Testes, epididymis and accessory glands measurements should be mandatory as an imminent for male selection. This study aimed at defining the ultrasonographic characteristics and measurements of testes, epididymis and accessory glands at different growth stages in Chios rams.Methods: Sixteen rams were assigned by age class into: group A (pre-pubertal, n=3), group B (pubertal, n=5) and group C (mature, n=8). Scrotal circumference (SC) was measured using a tape. Scrotal contents were examined using a B-mode ultrasound. Testicular breadth (TB), thicknesses of tunica albuginea (TA) and mediastinum (MS) and the largest dimension of epididymal tail (EpT) were estimated. Trans-rectal ultrasound was carried out to estimate the echogenicity and diameter of bulbourethral gland (BUG), height of pars dessiminata of prostate (PDP) and maximum breadth of seminal gland (SG).Result: SC increased curvilinear with age. Testicular echogenicity increased with age. Thickness of TA did not differ with age. MS could not detect in pre-pubertal rams, reached maximum thickness with puberty and became relatively thinner by maturity. EpT evidently enlarged with puberty. BUG, PDP and SG exhibited moderate echogenicity. They reached their greatest size with sexual maturity. SC estimated by tape and TB estimated by US correlated with most of the ultrasonographic measurements of the epididymis and accessory glands.

Some Cretaceous long-looped terebratulide brachiopods analysed in the light of the diversity observed in the ontogeny of Recent representatives

2003 ◽  
Vol 174 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Danièle Gaspard
Keyword(s):  
Early Ontogeny ◽  
Early Growth ◽  
Growth Stages ◽  
Serial Sections ◽  
Median Septum ◽  
Wide Range ◽  
Growth Types ◽  
Fossil Records ◽  
Similar Growth ◽  
Main Growth

Abstract The shape of the loop is of prime importance in brachiopod terebratulide classification and has been widely discussed and revised [Williams et al., 1996]. In the Rhynchonelliforma, we have focused our attention on the Terebratellidina, long-looped brachiopods with a wide-range diversity. The observation of its internal structure in recent representatives, investigated from the early growth stages, using the Scanning Electron Microscope (S.E.M.), demonstrates the complexity of its growth. Two main growth types of the descending branches are expressed during early ontogeny [Gaspard, 2002], followed in both cases by forward growth in opposite directions, with a brachial ribbon attached or unattached to the median septum. The purpose of such observations is to find in the fossil records similar growth types. An approach from the recent representatives allows a better knowledge of the Cretaceous taxa considered, even if the only way to recognise the loop is by means of transverse serial sections. The study of the recent terebratellidine loop facilitates the establishment of links between species from different geological periods. It helps to determine superfamilial distinctions and to find possible ancestors of recent terebratellidines.

scholarly journals Morphological variability in populations of the fiddler crab Leptuca uruguayensis (Nobili, 1901) (Crustacea, Decapoda, Ocypodidae) from South America

2017 ◽  
Vol 65 (3) ◽  
pp. 373-381 ◽  
Author(s):  
Setuko Masunari ◽  
Salise Brandt Martins ◽  
Murilo Zanetti Marochi ◽  
Wilson Sebastián Serra ◽  
Fabrizio Scarabino
Keyword(s):  
Posterior Margin ◽  
Sexual Maturity ◽  
Growth Analysis ◽  
Fiddler Crab ◽  
Carapace Width ◽  
Morphological Variability ◽  
Centroid Size ◽  
Relative Growth ◽  
Abiotic Variables ◽  
Major Cheliped

Abstract A comparative study on size and shape of Leptuca uruguayensis was carried out between populations from Garças River, Brazil (BP), and Solís Grande River, Uruguay (UP). The size of the onset of sexual maturity was also estimated for UP. A total of 36 crabs BP and 387 crabs UP were analyzed. In the relative growth analysis, carapace width (CW) for both sexes, major cheliped length (LMC) for males and abdomen width (AW) for females were measured. The centroid size of carapace (1.40±0.19 cm BP and 1.88±0.30 cm UP) and cheliped (1.16±0.22 cm BP and 1.58±0.45 cm UP) differed significantly (p<0.001). The shape also differed significantly (p<0.001), having UP wider carapace than BP, rostrum projected forward and posterior margin positioned more anteriorly; the cheliped of UP was also wider than BP. In UP, males' CW ranged 4.28-19.5 mm and females' 2.53-16.3 mm CW; males' LMC ranged 1.79-31.60 mm and females' AW, 0.80-8.53 mm. The onset of sexual maturity of UP was estimated in 12.20 mm CW for males and 7.81 mm for females. These differences are likely related to abiotic variables acting distinctly in the two localities.

scholarly journals Life history of Tendaguru sauropods as inferred from long bone histology

Fossil Record ◽  
1999 ◽  
Vol 2 (1) ◽  
pp. 103-112 ◽  
Author(s):  
P. M. Sander
Keyword(s):  
Life History ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Sexual Maturity ◽  
Upper Jurassic ◽  
Bone Histology ◽  
Long Bone ◽  
Large Mammals ◽  
Growth Series ◽  
History Of

Abstract. Sauropod dinosaurs present exceptional challenges in understanding their biology because of their exceptional body size. One of these, life history, can be inferred from the histology of their bones. For this purpose, the diverse sauropod assemblage of the Upper Jurassic Tendaguru beds was sampled with a new coring method which provided unprecented access to and insights into sauropod bone histology. Growth series of humeri and femora as well as long growth records from single bones suggest that all four sauropod taxa are characterized by continued growth after sexual maturity but that growth was determinate. Fibrolamellär bone is dominant in the samples, indicating that the bones of the Tendaguru sauropods grew at rates comparable to those of modern large mammals. The growth pattern of these sauropods thus combines typically reptilian traits with typically mammalian traits. In the details of their bone histology, the Tendaguru sauropod taxa show considerable variation which reflects life history. In addition, Barosaurus exhibits probable sexual dimorphism in bone histology. Das Verständnis der Biologie der sauropoden Dinosaurier wird durch ihre enorme Körpergröße außerordentlich erschwert. Allerdings kann ein Aspekt, die Lebensgeschichte, anhand der Histologie ihrer Knochen untersucht werden. Zu diesem Zweck wurde die diverse Sauropoden-Vergesellschaftung der oberjurassischen Tendaguru-Schichten beprobt, und zwar mit einer neuartigen Kernbohrmethode, die einen herausragenden Zugang und Einblick in die Knochenhistologie der Sauropoden ermöglichte. Wachstumsserien von Humeri und Femora sowie umfassende Überlieferungen des Wachstums von Individuen anhand einzelner Knochen machen es wahrscheinlich, daß alle vier Sauropoden-Taxa der Tendaguru-Schichten durch ein auch nach der Geschlechtsreife anhaltendes Wachstum gekennzeichnet waren. Allerdings ging das Wachstum nicht bis zum Tode des Tieres weiter, sondern kam bei einer etwas variablen Maximalgröße zum Stillstand. Fibrolamellärer Knochen ist der vorherrschende Knochentyp in den Proben, was anzeigt, daß die Tendaguru-Sauropoden mit für Säugetieren typische Raten wuchsen. Die Tendaguru-Sauropoden kombinerten also ein für Reptilien typisches Muster des Wachstums, nämlich nach der Geschlechtsreife anhaltendes Wachstum, mit für Säuger typischen Raten des Wachstums. Die verschiedenen Sauropoden-Taxa zeigen erstaunliche Unterschiede in den Details ihrer Knochenhistologie, die Unterschiede in der Lebensgeschichte belegen. Bei Barosaurus scheint außerdem ein Geschlechtsdimorphismus in der Histologie der Langknochen vorzukommen. doi:1002/mmng.1999.4860020107

Mandibular force profiles and tooth morphology in growth series of Albertosaurus sarcophagus and Gorgosaurus libratus (Tyrannosauridae: Albertosaurinae) provide evidence for an ontogenetic dietary shift in tyrannosaurids

2021 ◽  
Author(s):  
François Therrien ◽  
Darla K. Zelenitsky ◽  
Jared T Voris ◽  
Kohei Tanaka
Keyword(s):  
Feeding Behavior ◽  
Feeding Strategy ◽  
Large Body ◽  
Biomechanical Properties ◽  
Bite Force ◽  
Growth Stages ◽  
Tooth Morphology ◽  
Growth Series ◽  
Dietary Shift ◽  
Force Profiles

The albertosaurines Albertosaurus sarcophagus and Gorgosaurus libratus are among the best represented tyrannosaurids, known from nearly complete growth series. These specimens provide an opportunity to study mandibular biomechanical properties and tooth morphology in order to infer changes in feeding behavior and bite force through ontogeny in tyrannosaurids. Mandibular force profiles reveal that the symphyseal region of albertosaurines is consistently stronger in bending than the middentary region, indicating that the anterior extremity of the jaws played an important role in prey capture and handling through ontogeny. The symphyseal region was better adapted to withstand torsional stresses than in most non-avian theropods, but not to the extent seen in Tyrannosaurus rex, suggesting that albertosaurine feeding behavior may have involved less bone crushing or perhaps relatively smaller prey than in T. rex. The constancy of these biomechanical properties at all known growth stages indicates that although albertosaurines maintained a similar feeding strategy through ontogeny, prey size/type had to change between juvenile and mature individuals. This ontogenetic dietary shift likely happened when individuals reached a mandibular length of ~58 cm, a size at which teeth shift from ziphodont to incrassate in shape and bite force begins to increase exponentially. The fact that large albertosaurines were capable of generating bite forces equivalent to similar-sized tyrannosaurines suggests that no significant differences in jaw closing musculature existed between the two clades and that the powerful bite of T. rex is the result of its large body size rather than of unique adaptations related to a specialized ecology.

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