Talk:Ernietta

A remark on the classification

Mikhail A. Fedonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, and Patricia Vickers-Rich foreword by Arthur C. Clarke. (2007) "The Rise of Animals. Evolution and Diversification of the Kingdom Animalia," Johns Hopkins University Press, p. 326)

A Plethora of Petalonamae ... And then there is a form called Ernietta - and Erniobaris, Erniaster,Erniobeta, Erniocarpus, Erniocentris, Erniocoris, Erniodiscus, Erniofossa, Erniograndis, Ernionorma, Erniopelta, Erniotaxis, etc., etc., etc., almost ad infinitum. Most, if not all, of these names appear to be what paleontologists call tapho-names. They are different forms of preservation, or different stages of growth, of one particular or a few species. Almost all have been combined, or synonymized, with Ernietta ptateauensis by Martin Pickford (1995), and this combining of names into one has been recognized by many (Runnegar. 1992, among others) Ernietta is an intriguing organism or a series of different organisms that apparently lived partly buried in the sediments, for they are found in place in sediments oriented perpendicular to the sediment-water interface and often occur in concentrated groups. They resemble sand-filled socks that apparently were composed of a series of parallel tubes, often constricted midway along the direction of growth by a prominent waist, but exactly what these structures reflect is still uncertain. Sometimes Ernietta specimens are found in place, and at other times they seem to have been transported. Some of the smaller forms, only a centimeter or two m diameter, occur as bulbous nodules that at a distance give the impression of a rhynchonellid brachiopod, likely only a superficial guise. They can be very abundant locally and thus far have only been found in the Kliphoek Member of the Dabis Formation, Nama Group. And just what was Ernietta? There is wide disagreement among those who have studied this petalonam. Some think it was a coelenterate-like form {Glaessner & Walter. 1975), but Jenkins (in Lipps & Signor, 1992) noted that It shows no close resemblance to any known member of this group. Jenkins further noted that Emietta seemed to have two phases of growth, separated by a distinct seam, indicating that "the basal part of the sack was complete or entire prior to upward growth of the side walls." He suggested that perhaps the juvenile form of Ernietta was rather discoidal in shape with up to 30 or so ribs or tubes on either side and may have been either pelagic or a bottom dweller. Once it reached maturity, perhaps it took up or continued its benthic or even partially infaunal lifestyle and grew upwards forming an elongate lube. He, like Martin Pickford, preferred to relate Ernietta to Pteridinium, placing both in the Phylum Petalonamae, originally suggested by Pflug {1972). In addition to these well-known and oft-abundant forms, many others are known, highlighting the biodiversity of this assemblage Orthogonium parallelum was first named by Gunch in 1930, and at the time he suggested that it might be allied with crinoids. Later Bruce Runnegar and Mikhail Fedonkm suggested that it was one of the "quilted' petalonams, but with its likely loss during World War II, its true identity will probably never be known Namalia is yet another name set up by Gerard Germs (1968) based on a conical fossil that he found on Farm Buchholzbrunn and later more on Farm Vrede in the Kuibis Formation. Namalia often occurs in large numbers, and individuals are round to oval in cross-section, with numerous longitudinal ridges. Sometimes Namalia is found within the sediments, narrow end down. Some have also been found in lag deposits on bedding planes, suggesting that they had been reworked and transported (Pickford. 1995). Bruce Runnegar (1992) suggested that Namalia was actually Ernietta plateauensis, simply one of its many growth or tapho-forms. Other Petalonamae include Paramedusium africanum, again named by Gunch, Nasepia altae, set up by Gerard Germs (1973), and Velanconna martina of Pflug (1966), all of which apparently were forms preserved flat, perhaps in life reclining on the sea floor (Pickford, 1995), certainly like many of the rangeomorphs from Newfoundland. Preferred Preservation Jerzy Dzik (1999) has noted that the three most common fossils in the Nama sequence, Rangea, Ptendinium and Ernietta, are generally not found together. Each has a preferred style of preservation, exclusive to each form Rangea, often with sand-filled basal discs and collapsed fronds, is found within sandstone that seems to represent mass flows (Jenkins. 1985) Ptendinium seems nearly restricted to storm-related sediments, massive sand layers in which fossils lack much of any preferred orientation (Jenkins. 1992; Seilacher, 1984). Dzik suggests that they were likely deposited together with the suspended sediment and "gradually loaded with sand while sinking." Emietta is entirely different, often occurring in dark reddish mudstone/siltstone/coarser sand, often with preferred orientations. Dzik notes that he observed only one block with Ernietta specimens in place, where they likely lived, but in 2003 a joint expedition of researchers from the Namibian Geological Survey accompanied by others from Australia and Russia found numerous blocks with in situ Ernietta, so this preservation style is not so uncommon as previously thought. Dzik (1999) suggests that some of the different shapes taken on by a variety of Ernietta specimens could simply be due to a sand-filled organism sinking into a water-saturated bottom sediment that had just been emplaced by down-slope avalanches during a storm-initiated event. How far the dead, sand-filled Ernietta sank would determine its final shape as a fossilized form. Dzik noted that the body wall of Ernietta would likely have been composed of a most flexible material, perhaps something like collagen, which would explain why it was able to "shape-shift." as it seems to have done. He notes that such a tissue as collagen Is very durable, much more resistant to decay than many other soft tissues, and this may explain why Ernietta fossils so often maintain detailed morphology. Following on with this reasoning he goes a step further, suggesting that the tubular structure so characteristic of Ernietta might have been three-dimensional "tubular boxes" surrounded by collagen, within which there were muscles - drawing an analogue with the myosepta present in the protochordate Branchiostoma. He suggests that these sorts of theoretical structures could have been preserved during Neoproterozoic times because collagen and polysaccharide decomposers were not present, and as they developed in the Cambrian, the type of preservation seen in forms such as Ernietta and Dickinsonia became impossible. ... Ernietta plateauensis Occurrence: Common Locality: Farm Plateau, Aus area, Namibia, southern Africa Rock Unit: Dabis Formation, Nama Group Other Names: Erniaster, Erniobaris, Erniobeta, Erniocarpus, Erniocentris, Erniocoris, Erniodiscus, Erniofossa, Erniograndis, Ernionorma, Erniopelta, Erniotaxis (all Pflug, 1972), and perhaps Baikalina (Sokolov 1972) Description: The body bilaterally symmetric and segmented. Body axis bent into snaps of U. Zigzag median dorsal suture line, at which the segments of sides meet alternatingly (Pickford, 1995, after Pflug, i966). Jenkins (in Lipps & Signor, 1992) noted that this form was rather sac-shaped Reference: Pflug, 1966, l972, Jenkins et al., 1981, Narbonne, 2005 Type Specimen: Geological Survey of Namibia GSM 283 (F429-H) (Pflug No 277) Classification: Phylum: Petalonamae; Family: Ernietida; Narbonne has recently allied with dickinsoniomorphs, but Genling et al. (2005) do not agree

Aleksey (Alnagov (talk) 09:21, 25 April 2010 (UTC))

Names: some questions

1. Was it Pflug or Pflugg?
2. What were P.'s given names?
3. What is the origin of the name Ernietta (presumably given by P.)?
4. In what publication was the species name Ernietta assigned?

yoyo (talk) 01:25, 4 June 2010 (UTC)

Osmotrophy

Despite what the term suggests, osmotrophy is not feeding by osmosis. But scientific accuracy should not be expected on Wikipedia.89.168.180.105 (talk) 08:00, 16 August 2012 (UTC)

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