Re: Quiz
: 6 sierpnia 2022, o 15:56
Tak. Teraz już powinno być z górki.
Teraz jeszcze należy odszukać dwie inne prace - o głowonogu i tylakocefalu - wskazujące na ich cechy sugerujące bytność w jasnych, płytkich wodach.Audo, D., Robin, N., Luque, J. et al. Palaeoecology of Voulteryon parvulus (Eucrustacea, Polychelida) from the Middle Jurassic of La Voulte-sur-Rhône Fossil-Lagerstätte (France). Sci Rep 9, 5332 (2019). https://doi.org/10.1038/s41598-019-41834-6 pisze:The interpretation that V. parvulus had apposition eyes suggests an allochthonous, shallow water origin. However, the presence of thecideoid brachiopod ectosymbionts on its carapace, usually associated to dim-light paleoenvironments and/or rock crevices, suggests that V. parvulus lived in a dim-light setting. This would support the less parsimonious interpretation that V. parvulus had superposition eyes. If we accept the hypothesis that V. parvulus had apposition eyes, since the La Voulte palaeoenvironment is considered deep water and had a soft substrate, V. parvulus could have moved into the La Voulte Lagerstätte setting. If this is the case, La Voulte biota would record a combination of multiple palaeoenvironments.
Natomiast Vampyronassa rhodanica niezaliczona, bo chodzi o nową pracę o tej wampirzycy:Vannier, J., Schoenemann, B., Gillot, T. et al. Exceptional preservation of eye structure in arthropod visual predators from the Middle Jurassic. Nat Commun 7, 10320 (2016). https://doi.org/10.1038/ncomms10320 pisze:visual hunter probably adapted to illuminated environments, thus contradicting the hypothesis that La Voulte was a deep-water environment. (...) Although the eyes of Dollocaris were undoubtedly acute, their ability to capture light and low sensitivity make them a priori better adapted to high or moderate light conditions than to the poorly illuminated environments predicted at La Voulte. Resolving this apparent paradox requires more detailed palaeoenvironmental studies and new data on the visual organs of animals (for example, other crustaceans) associated with thylacocephalans in the La Voulte exceptional biota.
Mnie osobiście niezupełnie przekonują te argumenty, jak w przypadku innych gatunków, życie w głębinach może wyprzedzać ewidentne przystosowania do niego.Rowe, A.J., Kruta, I., Landman, N.H. et al. Exceptional soft-tissue preservation of Jurassic Vampyronassa rhodanica provides new insights on the evolution and palaeoecology of vampyroteuthids. Sci Rep 12, 8292 (2022). https://doi.org/10.1038/s41598-022-12269-3 pisze:The data obtained here suggests that V. rhodanica, the purportedly oldest-known genus of the Vampyromorphina group, was an active predator following a pelagic mode of life.
Indeed, several anatomical details, mainly found in the brachial crown, seem to support this hypothesis. Though we cannot directly compare functionality of the arm crown elements with other Jurassic taxa, we can infer function based on observation in modern forms. In Octopoda, the sister group to Vampyromorpha, suckers are attached to the arm by a cylindrical layer of muscle, encircling oblique musculature40,41, that connects the arm musculature and the lateral margin of the acetabulum34,40,41,42. This facilitates a variety of functions including locomotion, manipulation, and prey retention43. The sucker attaches by flattening the infundibulum against the surface and then the encircling epithelium creates a watertight seal36,40,41,42,43,44,45. Contraction of the radial acetabular muscles provides the pressure differential required to create the suction force43,44,46.
The stalked sucker attachments2,34 of decabrachians (Fig. 3d, and Supplementary Fig. 4) are muscular35 and connect the musculature of the arm with the base of the sucker, forming part of the acetabulum33,34. Tension on the sucker stretches this muscular attachment, which pulls locally on the acetabular base. This facilitates a greater pressure differential inside the sucker, allowing the teeth on the sucker ring to maintain the hold47.
Extant V. infernalis lack decabrachian-like stalks2,18 and the neck of the attachment joins to the base of the acetabulum (Fig. 3c, and Supplementary Fig. 4), rather than being inserted into it18. The infundibulum is not distinct, and the suckers do not provide strong suction27. Instead, suckers function by secreting mucus to coat detritus—marine snow captured by retractable filaments—which is then moved to the mouth by cirri7,27.
A mosaic of these characters is present in V. rhodanica (Fig. 3a,b), therefore, suggesting their potential for increased attachment and hold on prey over extant V. infernalis. These include a larger infundibular diameter, a neck attachment integrated with the acetabular muscles, and the elongated stalks of the dorsal suckers.
Additionally, the paired, filamentous cirri observed in extant cirrates48 are present in V. rhodanica (Fig. 4, and Supplementary Fig. 2). In extant forms they are understood to have a sensory function and are used in the detection and capture of prey48. In V. infernalis, they serve to transport the food proximally along the arms to the mouth27. The greater diameters of cirri, and placement along the entire arm in V. rhodanica (Fig. 4), suggests an increased sensory function in these fossil forms.
The shape of the arms also contributes to the suction potential49 in coleoids. Functional analysis in Octopoda highlights a positive correlation between distal tapering of the arms and their flexibility. A tapered, flexible arm facilitates more precise adhesion than a cylindrical-shaped one and requires a greater force for sucker detachment49. Suckers detach sequentially, rather than the more simultaneous release observed in models of arms with less taper variation. The tapered diameter of the suckers, like those seen on the sessile arms of V. rhodanica, potentially facilitated this kind of sequential detachment49 allowing them more adherence force and flexibility. Though V. rhodanica has just two suckers on the distal tips of their dorsal arms, the most distal is marginally smaller in diameter than the proximal one. On the dorsal arms, this tapering is observed in conjunction with a well-developed axial nerve cord (Fig. 2b). In extant forms, the nerve cord facilitates complex motor functions42. The combination of these characters in V. rhodanica suggests their arms had increased potential to be actively used in prey capture50 over extant V. infernalis.
Wrzucony przeze mnie okaz to właśnie MNHN.B.74244, pochodzi z ww. pracy (suplementu).Rowe et al. pisze:The luminous organs described by Fischer & Riou16 could not be confirmed, though two dense, somewhat ovoid structures are located within the peripheral mantle tissue at the posterior-most area of the body in specimen MNHN.F.74244 (Supplementary Fig. 6). These dense structures are in a similar position to the luminous organs noted in the original description by Fischer & Riou16, though are 4–5 times larger in MNHN.F.74244. They are only observable in the tomographic image and do not appear in the other two specimens.
(...)
Rather than luminous organs much larger than those present in the deep-sea, extant V. infernalis, it is possible that these structures represent displaced cartilage prior to fossilization (Supplementary Fig. 6).