Fossil scaphopods aren’t well studied, the Jurassic period isn’t an exception. The number of publications dealing with this subject can be counted on the fingers of one hand. So, we are extremely lucky this literature gab is partly filled due to a publication by A. V. Guzhov from the Borissiak Paleontological Institute of the Russian Academy of Sciences. The paper, titled ‘Jurassic Scaphopoda from the Russian Platform: Pulsellidae and Gadilidae’, is published in Paleontological Journal and can be accessed/purchased at Springer.
All described and figured material is from the European part of Russia. Which means that some extremely remote localities are included. Due to these rare localities and the lack of other research results in the fact that all 13 listed species are described as new by the author. The publication also lists 4 new genera (i.e. Gracilipulsellum, Gardneridentalium, Mesoentalina and Mesoantalis) and one new subgenus of Annulipulsellum (i.e. Mesopulsellum). A list of all 13 new species can be found below.
Alexandr said he will continue with research on taxonomy of scaphopods. So, we will most likely hear more from his side!
Guzhov, A., 2017. Jurassic Scaphopoda from the Russian Platform: Pulsellidae and Gadilidae. — Paleontological Journal, 51(1): 13–29, 14 figs.
I haven’t posted anything on my blog for a while, due to a lack of time. It is my intention to start publishing about my activities and the activities of my friends more regularly here.
This is the first of a series of posts called “Important Scaphopod Publications”. There is still a big gap in the availability of (older) works online. The main problem is that scanning large amounts of documents is expensive. This is the reason why we find poor scans online and institutions start asking insane prices for just a few pages. Luckily, for the private/amateur researchers, there are several good projects nowadays (such as BHL, GDZ and for Dutch journals natuurtijdschriften.nl). In this series I’ll publish some of the scaphopod publications from own scans. Making these works available is done with both the permission of the author(s) and the publisher. Please contact me if there is any problem or if you want to contribute in this project.
This work by Giulio Pavia, although already backdating to 1991, still is the best work with regards to the Italian Miocene. This work lists three new species and (maybe more importantly) synonymized several taxa. The nomenclatural actions render it important enough to make this work available online (you can find the link to the pdf above).
IMPORTANT: Giulio told me (in litt.) that there is a significant change in the stratigraphy of the Borelli site. Based on studies on planktonic foraminifera the site is now referred to the middle-upper part the Tortonian, which was confirmed by nanoplanktonic and holoplanktonic mollusc studies by Arie Janssen in 2010.
Thanks to Giulio Pavia, who allowed to distribute the pdf in this website.
The last workshop was few months ago and we come already closer to the next workshop. The report on the 3rd European workshop on scaphopod molluscs is published in Spirula (journal of the Dutch Malacological Society) this week. You can read and download the report here: LINK. Please enjoy reading and mail your comments and compliments.
Below you can enjoy a video of the first cleavage of a Pulsellum spec. dredged in Friday Harbor, San Juan County, Washington, United States. The dark region in the video is the pink cytoplasm, which gets sorted as the egg proceeds toward first cleavage into a prominent equatorial band. This video was taken by George von Dassow and originally published on his website about cell behavior during animal development on March 9th, 2010. The accompanying text is written by Katie Bennett and George von Dassow.All rights are reserved by George von Dassow.
Half-way through this movie you might ask yourself, what is that funny three-celled embryo? How can it have three cells? Is it normal? If one found a single three-cell embryo in a culture of normal-looking two-cells, one would assume it was polyspermic or otherwise defective. But what about a whole dish of them? This apparent three-cell – or trefoil – stage is a normal feature of early development for many molluscs and annelids. The scaphopod featured here, a predatory infaunal mollusc with a tube-shaped shell, exhibits classic polar lobe formation: the extrusion and transient partition of a large parcel of cytoplasm which is subsequently resorbed into one daughter cell.
As in this case, segregation of the polar lobe cytoplasm at the vegetal end of the embryo results in a protrusion so constricted that it appears to be a third cell. This is remarkable for two reasons: first, the polar lobe is a mechanism for cell fate specification; second, it is a cytokinetic puzzle. In animal cells, the cytokinetic furrow always crosses the midplane of the mitotic apparatus. That’s how the cell ensures that the cell division plane passes between carefully-sorted sets of duplicated chromosomes. In polar-lobe-forming cells, of course there is only a single mitotic apparatus, bisected by the “normal” furrow. How is the furrow around the neck of the polar lobe induce? There are several possible explanations, but all of them are speculative.
However it forms, what embryologist could resist the temptation of experimentally removing such a tidy bundle? This experiment has been performed on several species, most famously by Clement on the snail Ilyanassa obsoleta. The results show that the contents of the polar lobe endow its lineage with something that makes one of its descendant cells behave as the organizer for the rest of the embryo. One interpretation would be that there is information essential for normal development contained within the polar lobe. The nature of that information, however, remains elusive, and another possibility is that the polar lobe just makes some cells bigger, and consequently different.
Some molluscs and annelids make small polar lobes. Others simply undergo an unequal first cleavage, without a polar lobe. But there is good reason to think that the ancestors of both molluscs and annelids probably cleaved equally, instead of determining the organizer lineage in the first few divisions. That means polar lobes have arisen several times during the evolution of existing molluscs and annelids. Why? Is there some reason, in the embryology of these groups, why many evolutionary lineages found it adaptive to speed up early cell fate specification? And are these embryos, for some reason, predisposed to come up with this peculiar mechanism of unequal division?
Thanks George von Dassow for allowing me to repost his material. More information about this particular species and its habitat will I publish later! To be continued!
Half past eight in the morning, Winterswijk (neighbourhood: Miste) is shrouded in fog. The pasture of dairy farmer Brethouwer fills slowly with determined people. All are searching for that special shell or that big shark tooth. The camera crew of Vroege Vogels is busy with filming the, maybe more interesting, unpack processs of the real fossil-enthusiasts. With complex constructions lots of sifters, shovels and storage equipment are fastened on the hand trucks and wheelbarrows. There’s a tense atmosphere and expectations are high. The last diggings found many beautiful fossils.
The euphoria is very great when organizer Stef Mermuys, after a short notice, cuts the barrier tape. Within a few minutes every one is busy with sieving. My first catch contains a Glycimeris, a piece of a Xenophora, two Naticas, a Typhis, a quite large Scaphopod and a lot of Aporrhais (Aporrhais) dingdenensis Marquet, Grigis & Landau, 2002. Fascinated by this Scaphopod and the hand of other common species, I was not concerned with what further lay ahead, but that slowly became clear later in the week.
Some great findings are a good hand of shark teeth, two great Chicoreus aquitanicus (Grateloup, 1833), an Apiocypraea subphysis septemtrionalis (Schilder, 1929), pieces of whale ribs, some turtle plates and 120 litres of other shells, shark teeth and small bones.
Hundreds of Scaphopods are in my grit. Other species than on previous diggings? No, not so far, but the composition and quantity of the species is maybe different. I’ve less material, not enough material yet to have a good view of the species diversity of Miste. I’m still looking for Scaphopods from this or previous diggings, to get a better view. Photos and suggestions can be emailed to: email@example.com.
I want to thank everyone who was at Miste and with whom was able to have a conversation. Of course I want to thank the Miste digging 2013 crew for their their commitment to a successful digging. People who are interested in the Vroege Vogel broadcasts: they can be looked and listened on Link and Link.
The journey went easy. When we arrived we were in luck that there was a meeting of “Club Conchylia”, so we were allowed to see some shells while enjoying a cup of tea and a lovely piece of home-made cake. We didn’t wait long before Karina Thiede and her husband arrived. I had made an appointment to get some great pieces of “Sternberger gestein”. A very Scaphopod-rich formation from the Chattium (A and B), Oligocene age. I will study those Scaphopods later.
The following days we tried to find an ID on our difficulties, but every solved problem gave us a lot more new questions. We also discussed some matters on anatomy, biology, distribution, morphology and nomenclature.
During our one-day discussion about the Red Sea Scaphopods, we have solved a lot of problems. The most things are more clear now and ready to publish. Vollrath has helped us with his photograph skills to make fantastic, detailed pictures of these white, striated shells.
I want to thanks Bernd and Vollrath for their hospitality, lot of information, and humoristic moments, Vollrath earns special honor for his photograph skills. We have laughed a lot, and the cakes were very tasteful. Thanks to Frans for his accompaniment during this trip.
The Deep Reef Observation Project (DROP) is a Smithsonian initiative in the island of Curaçao which began in 2011 with support from the Consortium for Understanding and Sustaining a Biodiverse Planet. I have been studying hermit crabs and other crabs that have been filmed or photographed using a manned submersible named Curasub, which can dive down to 300 m in depth. A rich and spectacularly colored fauna of hermit crabs, never seen before alive in their original habitats, has been discovered.
The DROP program is providing an extraordinary and unique opportunity for taxonomists like me to make direct, live observations of many species that have previously been known exclusively from preserved and colorless specimens in museum collections. The study of these samples, such as those of Pylopagurus discoidalis shown here, is serving to expand and complement collaborative studies on hermit crabs systematic from the Caribbean at large. The specimens are being used to obtain molecular data such as barcodes and DNA sequences, which will be useful for biodiversity assessments, long-term faunal monitoring, and evolutionary studies.