Odontoma found in a Late Permian Gorgonopsian Synapsid from Tanzania.

Odontoma is a condition known in a variety of Mammal species in which small tumours appear in the jaw, made up of differentiated tooth material with differentiated enamel and dentine. This can lead to the re-absorption of the roots of the functional teeth, resulting in tooth loss. This condition has been detected in the recent fossil record, in species such as Mammoths up to a few million years old, and can be expected to have existed in the common ancestor of all the animals in which it has been recorded (Humans, Horses, Mammoths and Deer), probably in the Late Cretaceous, its presence earlier in the fossil record is unknown.

In a paper published in the journal JAMA Oncology on 8 December 2016, Megan Whitney, Larry Mose and Christian Sidor of the Department of Biology at the University of Washington, describe a case of odontoma in a 255-million-year-old Gorgonopsian Synapsid from the collection of the National Museum of Tanzania.

Synapsids split from the ancestors of modern Reptiles and Birds about 320 million years ago. Today the only surviving Synapsid group are the Mammals, but in the Permian a diverse range of Synapsids dominated most terrestrial ecosystems. The Gorgonopsians diverged from the ancestors of Mammals before the development of traits such as large brain size, diphyodonty, distinct thoracic and lumbar vertebrae, and 3 middle ear ossicles, though they did have Mammalian traits such as differentiated teeth and an upright gait.

Whitney et al. worked upon a right dentary (jawbone) of an unnamed Gorgonopsian. The specimen was embedded in polyester resin, then cut it into a series of thin sections, which were ground down to a thickness of approximately 100 μm using a variable-speed grinder and polisher. This revealed a series of eight ectopic toothlike lessons, close to the labial edge of the functional canine root. These range in size from 0.3 to 3.9 mm, some of which incur into the root of the tooth, causing loss of the cementum and dentine.

(A) Computed tomogram of a Gorgonopsian anterior dentary (red) with dentition (blue) highlighted (National Museum of Tanzania specimen RB382), indicating approximate positions of thin sections where the pathologic features are visible (National Museum of Tanzania specimen RB404). Successive slides representing the cervical (B) and midroot (C) portions of the functional root with odontomes. (D) Clustering of odontomes at the apical end of the tooth root. All histologic images were taken under cross-polarized light. Ca indicates root of canine; d, dentine; e, enamel; i, root of incisor; od, odontome; and pc, root of postcanine. Whitney et al. (2016). 

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The clear skies of GJ3470b.

GJ3470b is a roughly Uranus mass planet (14.1 times the Earth's mass, as opposed to Uranus's 14.5 Earth masses), 82 light years from Earth in the constellation of Cancer, orbiting a Red Dwarf star with roughly 54% of the Sun's mass. It orbits its star at approximately 3.6% of the distance at which the Earth orbits the Sun, with a year of only eighty hours, for which reason it has been described as a Hot Uranus.

An artists impression of GJ3470b. National Astronomical Observatory of Japan.

GJ3470b is a transiting exoplanet seen from Earth; it passes in front of its star from out viewpoint, potentially allowing us to calculate its density and study its atmosphere. In a paper published in the Astrophysical Journal on 29 May 2013, and on the online arXiv database at Cornell University Library on 30 May 2013, a team of scientists led by Akihiko Fukui of the Okayama Astrophysical Observatory discuss the results of a study of GJ3470b at optical and near-infrared wavelengths.

Fukui et al. conclude that GJ2470b has an approximate average density of 0.94 g cm¯¹, compared to 1.27 g cm¯¹ for Uranus or 5.515 g cm¯¹ for Earth (or 1.0 for water). This is an average figure, and includes the atmosphere, plus any liquids or solids on the planet, it does not imply the planet is the same throughout. Fukui et al. suggest that the best fit for this density would be a planet with a small rocky core, surrounded by a thick layer of water or ice and a hydrogen rich atmosphere. Furthermore they conclude the atmosphere can be no more than 10% of the total mass (any more and it would boil away) and that the water/ice layer has approximately three times the mass of the rocky part.

They were also able to measure some of the optical properties of the atmosphere. If GJ3470b had a thick cloudy atmosphere it would appear as a solid disk, with little variation in the light it blocked from its parent star, whereas it is possible to detect two dips in stellar output as it crosses the disc of the star, which Fukui et al. conclude represent partial blocking of the star's light by the atmosphere and complete blocking by the planetary core; suggesting that GJ3470b has a reasonably clear atmosphere, lacking a thick cloudy layer. From this they suggest future studies my be able to examine the molecular composition of this atmosphere.

Diagram showing how an observer can detect a non-opaque atmosphere on a transiting planet. National Astronomical Observatory of Japan.

See also The atmosphere of GJ 1214b, Kepler 69c; a Super Venus rather than a Super Earth? The atmosphere of Wasp 12b, Two new views of τ Boötis b and Thermal imaging 55 Cancri e.

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Two Hot Jupiters found in the Beehive Cluster.

The Beehive Cluster (also M44, Praesepe, the Manger) is an open cluster (a group of stars in close proximity presumed to share a common origin) 577 light years from Earth in the constellation Cancer. It is 22.8 light years across, contains over a thousand stars and is believed to be roughly 600 million years old.

M44, the Beehive Cluster. Greg Parker/The New Forrest Observatory.

In a paper published on the online arXiv database at Cornell University Library on 3 July 2012, a team of scientists led by Samuel Quinn of the Department of Physics & Astronomy at Georgia State University, describe the discovery of two Hot Jupiter type planets within the Beehive Cluster, using the 1.5-m Tillinghast Reflector at the Fred L. Whipple Observatory on Mt. Hopkins in Arizona.

The first of the new planets is named Praesepe 0201b. This orbits the star Praesepe 0201, an F class Dwarf Star 1.234 times the Sun's mass and an effective surface temperature of 6174 K (our Sun has an effective surface temperature of 5778 K). The planet has a mass 0.54 times that of Jupiter, and completes one orbit every 3.43 days.

The second planet is Praesepe 0211b, which orbits the star Praesepe 0211, a G-type dwarf star (the same class of star as out Sun) with 0.952 of the Sun's mass, and an effective surface temperature of 5326 K. The planet has a mass 1.844 times that of Jupiter, and completes one orbit every 2.15 days.

See also Two new views of τ Boötis b, Planets discovered orbiting the ancient, second generation star HIP 11952, The atmosphere of WASP-24b, Cooking the planets if CoRoT-7 and Exoplanets on Sciency Thoughts YouTube.

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