Ledumahadi mafube: A giant Sauropodomorph Dinosaur from the Earliest Jurassic of South Africa.

Sauropod Dinosaurs are the largest known land animals ever to have walked the Earth, with some species reaching masses of around 60 tonnes, larger than any member of any other Dinosaur group, and exceeded only by the modern Baleen Whales (which are fully marine in nature). These Dinosaurs descended from the Prosauropods, a polyphyletic group (i.e. a group which does not include all the descendants of their most recent common ancestor, since Sauropods are not considered to be Prosauropods; polyphyletic groups are not considered valid by many modern taxonomists) which includes early bipedal forms, and which may have split of from other Dinosaur groups before the Ornithischia/Saurischia split, with the two groups being together known as the Sauropodomorphs.

In a paper published in the journal Current Biology on 28 September 2018, Blair McPhee of the Departamento de Biologia at the Universidade de São Paulo, and the Evolutionary Studies Institute at the University of the Witwatersrand, Roger Benson, also of the Evolutionary Studies Institute at the University of the Witwatersrand, and of the Department of Earth Sciences and of the University of Oxford, Jennifer Botha-Brink of the National Museum in Bloemfontein and the Department of Zoology and Entomology at the University of the Free State, Emese Bordy of the Department of Geological Sciences at the University of Cape Town, and Jonah Choiniere, also of the Evolutionary Studies Institute at the University of the Witwatersrand, describe a new species of giant Sauropodomorph Dinosaur from the Earliest Jurassic of southern Free State, South Africa.

The new species is named Ledumahadi mafube, where 'Ledumahadi' means 'a giant thunderclap' and 'mafube' means 'dawn', both in Southern Sotho, in reference to the large size of the species, and its place early in the history the group. The species is described from a partial cervical neural arch, several dorsal vertebrae, a partial conjoined primordial sacral vertebrae, an anterior and a middle caudal vertebrae, an anterior chevron, a right ulna, a first metacarpal, a left metacarpal, probably III or IV, the distal third of the right femur; and a pedal ungual, all from Beginsel Farm, a location 25 km southeast of the town of Clarens in Free State Province, and close to the the border with Lesotho.

Selected Preserved Elements of Ledumahadi mafube and Geography and Stratigraphy of Type Locality. Preserved bones (A–K) are as follows: (A) middle/posterior cervical vertebra in left lateral view; (B) anterior dorsal vertebra in anterior and right lateral views; (C) middle dorsal vertebra in posterior and right lateral views; (D) first and second ‘‘primordial’’ sacral vertebrae in left lateral view; (E) anterior caudal vertebra in left lateral view; (F) right ulna in proximal and medial views; (G) first metacarpal in proximal and ?dorsal/ventral views; (H) left ?third metacarpal in proximal and ventral views; (I) pedal ungual in ?lateral and proximal views; (J) anterior chevron in posterior view; and (K) distal right femur in distal, lateral, and anterior views. (L) Simplified geological map of the Elliot Formation in the Republic of South Africa and Lesotho indicating the location of farm Beginsel 346 and aerial extent of the Elliot Formation outcrop area. (M) Landscape view of the local geology at the Ledumahadi site. Note that the contact of the lower and upper Elliot Formations (LEF and UEF, respectively) has been identified at 1685 m above sea level; thus the UEF is 60 m thick. The poorly exposed LEF, which is 10 m thick here, only contains massive mudstones with very weakly developed pedogenic alteration features, green-gray mottles, and very rare desiccation cracks. Abbreviations: ap, anterior process; ns, neural spine; op, olecranon process; poz, postzygapophysis; rf, radial fossa; sr, sacral rib; tfc, tibiofibular crest; vt, ventral tubercle. All scale bars represent 5 cm. McPhee et al. (2018).

The specimen is thought to have been about 14 years old at the time of its death, based upon dark rings in its long bones representing annual temporary decreases in growth due to seasonal climatic variation, though such ages are not completely precise, as the evidence of the earliest bone development is destroyed by secondary remodelling, and to have weighed about 12 tonnes, with fore-limbs modified into column-like forms similar to those seen in later Sauropods. Since Ledumahadi mafube is not thought to be ancestral to these forms, it represents a remarkable independent and parallel development of both rapid growth and column-like forelimbs from a bipedal ancestor in a separate Sauropodomorph group, which occurred shortly after the End Triassic Extinction. This is particularly notable as Ornithischian Dinosaurs, which underwent several separate transitions from a bipedal to a quadrupedal gait, never evolved column-like forelimbs, suggesting that making this transition was an ability unique to Sauropodomorphs.

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The evolution of Galeommatoid Bivalves.

Galeommatoid Bivalves are a large group of Molluscs that inhabit a broad range of environments and often form commensal relationships with a broad range of other invertebrates. Their classification has been somewhat uncertain, with the group divided into either two (Galeommatidae and Lasaeidae) or four (Galeommatidae, Lasaeidae, Kelliidae and Montacutidae) families.

In a paper published in the journal BMC Evolutionary Biology on 6 September 2012, a group of scientists led by Ryutaro Goto of the Graduate School of Human and Environmental Studies at Kyoto University and the Department of Marine Ecosystem Dynamics at the Atmosphere and Ocean Research Institute at The University of Tokyo, publish the results of a genetic study into relationships within the Galeommatoid Bivalves.

Goto et al. found that the Galeommatoid Bivalves are split into six clades (distinct evolutionary lineages), but that these bore no relationship to either previous classification of the group. 

Galeommatoid Bivalves are known to colonise a number of very different invertebrate hosts, notably Crustaceans, Sea Cucumbers, Spoon Worms, Sipunculan Worms, Brachiopods, Bryozoans, Annelids, and other Bivalves. Typically when epibiotic animals (animals that live on the surface of other organisms) switch hosts they do so between closely related species, with jumps between distantly related species being rare. However each clade of Galeommatoid Bivalves contained species which lived on very different hosts, with host species apparently being no guide to relationships within the Galeommatoid Bivalves. When parasites colonise new hosts they have to learn to get past the defences of the new organism, however Galeommatoid Bivalves are not true parasites; they live on the bodies of other invertebrates but gain nutrition by filter feeding from the water column, and few (if any) animals seem to have defences against this sort of colonisation, apparently making it easy for Galeommatoid Bivalves to switch between unrelated hosts.

The Galeommatoid Bivalve Arthritica japonica that attaches directly onto the body surface of intertidal Crabs. Goto et al. (2012).

Neaeromya rugifera that attaches onto the abdomen of Upogebid Shrimps. Goto et al. (2012).

Devonia semperi (top) and Anisodevonia ohshimai (bottom), which attach to the body surfaces of the burrowing Sea Cucumbers. Goto et al. (2012).

Byssobornia yamakawai on an Echiuran (Spoon) Worm. Goto et al. (2012).

Litigiella pacifica on the body of the Sipunculan worm, Siphonosoma cumanense. Goto et al. (2012).

Finally Goto et al. identified four ways in which Galeommatoid Bivalves colonised their hosts. Two of these, living inside shells used by Hermit Crabs and living inside the esophaguses of Sea Cucumbers, were utilised by single species, suggesting that these were unique evolutionary innovations, with little taxonomic significance. The remaining two methods, colonising the surface of the bodies of the host animals, and colonising the burrows of the hosts, were found in a variety of unrelated forms, suggesting that Galeommatoid Bivalves are also able to switch easily between these lifestyles.

The Galeommatoid Bivalve Ephippodonta gigas that lives in the burrows of Thalassinidean Shrimps. Goto et al. (2012).

Curvemysella paula, lives inside shells carried by Hermit Crabs. Goto et al. (2012).

This suggests that Galeommatoid Bivalves are extremely elastic in their ability to colonise new hosts and therefore new environments, which helps to explain the success of the group, even if it does make its taxonomy difficult to understand.

See also Symbiosis and the success of Galeommatoid Bivalves, The biology of pumice rafts, Deep-sea Gastropods from Miocene Cold Seeps and Whale-falls in Japan, Thirteen new species of interstitial Gastropods from New Zealand, and A new species of Scallop from Western Australia.

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New Glass Sponges from the North Atlantic.

Sponges are considered to be the most primitive form of animals. They lack differentiated cells, and can reform if disassociated by (for example) shoving them through a sieve. On the other hand they cannot be considered colonies of single-celled organisms, as they have definite structures, bodies with more-or-less set shapes consisting of networks of pores and channels through which water is pumped; the individual cells feeding separately by filtering food from the water in these channels.

Recent application of genetic methods to the classification of sponges have led to major revisions of the taxonomy of the group, with many Sponges that had been considered closely related now known to be at best distant cousins, with body plans apparently able to evolve quickly in response to environmental  conditions, leading to the frequent development of similar morphologies in different lineages, something evolutionary biologists call 'parallel evolution'.

One group that was thought to be immune to this problem were the Glass Sponges, or Hexactinellid Sponges, which live in deep water (down to 900 m) and which secrete skeletons made up of siliceous (glass) spicules, skeletal elements that help support the sponges body. This group have traditionally been classified on the morphology of their spicule skeleton in the same way that Vertebrates have been on their bone skeleton.

In a paper published in the journal Zootaxa on 10 July 2012, a team of scientists led by Martin Dohrmann of the Department of Invertebrate Zoology at the National Museum of Natural History, part of the Smithsonian Institution, present the results of a genetic study into North Atlantic Glass Sponges formerly classified in the genus Rossella.

There are twenty known species of sponges in the genus Rossella found in the Southern (Antarctic) Ocean, and (until now) a single species, Rossella nodastrella, from the North Atlantic. However Dohrmann et al. have demonstrated that these North Atlantic Sponges are not closely related to other members of the genus Rosella, and furthermore that the 'species' is in fact comprised of two genetically distinct, but morphologically identical populations (cryptic species).

Dohrmann et al. create a new genus Nodestrella, to classify these two species, with the first species (including the first population discovered) named Nodestrella nodestrella, and the second species named Nodastrella asconemaoida. Nodestrella nodestrella is known from the Azores and the deep waters off the coast of Florida, near Cape Canaveral. Nodastrella asconemaoida is also known from the waters off Cape Canaveral, as well as from the Miami Terrace in the Straits of Florida, and Rockall Bank, Ireland.

A specimen of Nodestrella asconemaoida on the Miami Terrace in the Straits of Florida. Dohrmann et al. (2012).

Scanning electron microscope image of part of the skeleton of Nodestrella nodestrella. Dohrmann et al. (2012).

 Skeletal elements from Nostrodella nostrodella. Dohrmann et al. (2012).

   Skeletal elements from Nostrodella asconemaoida. Dohrmann et al. (2012).

See also The oldest animals - Pre-Ediacaran Sponges from Namibia(?)

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