Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321

Serpulid (Annelida, Polychaeta) Evolution and Ecological Diversification Patterns During Middle-Late A.P. Ippolitov Geological institute of RAS, Pyzhevski lane 7, 119017, Moscow, Russia (E-mail: [email protected])

Tube-dwelling of families Serpulidae, and in Jurassic (middle Callovian to lower Spirorbidae and are extremely widespread, Oxfordian, uncertain) – only 6 species. For Boreal but poorly studied group of Mesozoic fossils. The main sections of Central Russia this pattern is similar: problems with serpulid study are: Callovian complexes count about 8 species only, while 1) Unclear and complicated systematics on tube in middle-upper Oxfordian there are about 12 species. features, which can not be easily coordinated and corre- Only few new generic taxa appeared in Berriasian and lated with modern systematics based on soft body were absent in Jurassic. There is no significant features; diversification at the level of genera. However, studied 2) Punctuated stratigraphical distribution, in most Lower Jurassic locations do not yield numerous and sections numerous serpulids occur only at one specific variable serpulids, neither in the author’s collection, nor level; in literature. Thus it can be deduced that generic 3) Unequal paleontological study of the group at diversification possibly took place during Middle different territories, absence of any knowledge/syste- Jurassic, when principal ecological and morphological matic descriptions for some areas. types formed, while during Middle-Upper Jurassic For the last decade the group attracts much atten- diversification took place at specific level. Phylo- tion of the researchers, and numerous papers are genetic scheme at generic level is impossible to draw published not only in , but also in tube micro- for the moment, since there is a “gap” in study for structures. Thus, the study of serpulids gradually comes Lower Jurassic–lower Middle Jurassic serpulids. to a new level, and first aspects of evolution and Moreover, Upper serpulid faunas of paleoecology can be drawn by coarse dabs at the Europe, detaily described in works of M. Jäger (1983, moment. 2004, and others), also do not contain principally new The fact is that total biodiversity rapidly grows morphotypes and genera of serpulid tubes comparing during the Mesozoic (there are about only 15 nominal with Jurassic and Berriasian faunas, possibly except for species described from the , about 150 – from numerous Pyrgopolon species. the Jurassic, and more than 200 – from Cretaceous The second fact is that tube morphotypes of deposits), and the most remarkable radiation took place different substrates are different, but in general features during Middle-Late Jurassic. The author has studied stable in time. The author has analysed all possible about 70 locations with Jurassic and Berriasian morphotypes of serpulid tubes and came to a con- serpulids in Central Russia and Crimea. It was shown, clusion that all tubes can be described with several that the main abiotic factor, which defines the parameters, all having morpho-functional interpretation: appearance of serpulid community, is the character of regular/irregular, large/average/small, attached/partly substrate-live (usually sponges, corals) or stagnant detached/free, fast growing/slowly growing. On live (belemnite rostra, concretions, ammonite shells, etc.). substrates and deposits of reefal tail predominate small Communities at the same substrate, but with different compact attached forms with tube diameter not wider stratigraphic position, consist of close species. Second than several mm (Metavermilia, Spiraserpula, Placo- principal parameter is hydrodynamics, serpulid com- stegus and many others), while at stagnant and stable munities in high-energy and low-energy sedimentary substrates substrate large irregular slowly growing conditions are different in species composition. serpulids (like Propomatoceros/Parsimonia) form the Comparison of similar sedimentary environment basis of the community. Of course, there are also and substrate at different stratigraphic levels allows us several forms which can be found on any kind of to give some conclusions on evolution and ecology substrate, like sabellid Glomerula of serpulid Filo- diversification in time, even when the fossil record is granula spp. very scarce. The diversification during Middle-Late Jurassic, The highest biodiversity of serpulid communities anyway, is marked by the first appearance of Conorca was documented in upper Berriasian of Crimea on morphotype and most ancient of spirorbids – sponges (33 species), and analogous community in representatives of Neomicrorbis – on live substrates lower Oxfordian contains only 14 species. Furthermore, (sponges). Recently it was shown by Taylor and Vinn in almost the same sections upper Berriasian Crimean (2007) that Paleozoic spiral spirorbis-like tubes are not communities on stagnant substrate it counts 20 serpulid relatives of modern Spirorbidae, which appeared

207 Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321 somewhere around Jurassic-Cretaceous boundary. Our Evolution; Adaptation investigation shows that first Spirorbids were already small and compact. This group derived from Serpulidae References: (for the last years it is proven also from molecular Jaeger M. Serpulidae (Polychaeta Sedentaria) aus dem phylogenetics), probably as an attempt to make tube norddeutchen hoheren Oberkreide – Systematik, small, which makes possible attachment to 1) flexible Stratigraphie, Okologie. Geologische Jahrbuch, substrates like algae in the upper sub-littoral zone; 2) Reihe A, 1983, bd. 68, s. 1-219. small free areas in densely inhabited biotopes and live Jaeger M. Serpulidae und Spirorbidae (Polychaeta substrates. This makes possible to effectively live in Sedentaria) aus Campan und Maastricht von high-energy and rich in food shallow-water environ- Norddeutschland, den Niederlanden, Belgien und ment. It is interesting that Conorca-like tubes have the angrenzenden Gebieten. Geologische Jahrbuch, same basic morphological characteristics as spirorbids Reihe A, 2004, bd. 157, s. 121-249. and can be considered as adapted to the similar Taylor P.D., Vinn O. Convergent morphology in small environment, thus there were a parallel evolution of two spiral worm tubes (‘Spirorbis’) and its palaeo- independent and concurrent braches of tubicolous environmental implications. Journal of the polychaetes. Geological Society (London), 2006, 163: 225-228. Key words: Serpulidae; Spirorbidae; Jurassic;

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