Symbiosis Between Lobsters and Bivalves During the Aptian Cretaceous

Bivalves on mecochirid lobsters from the Aptian of the Isle of Wight: Snapshot on an Early Cretaceous palaeosymbiosis

Authors:

Robin et al

Abstract:

Fossil symbioses (Bary 1879) that are not recognized in modern assemblages are rare. This holds true especially because fossil remains of interspecific association are sporadic and difficult to document. Thus, fossil associations illustrated on a large number of specimens are of particular interest. Numerous specimens of mecochirid lobsters (Glypheidea, Decapoda, Crustacea) from the Lower Cretaceous of the Atherfield Clay Formation (Isle of Wight, UK) seer small epibiotic bivalves on their exoskeleton. We propose to identify the post-mortem or syn-vivo nature of this association. To this end, we test and revise the systematic assignment of both crustacean and molluscan partners. A new genus name is proposed for the crustacean Meyeria magna M'Coy, 1849, as well as the new combination Atherfieldastacus magnus (M'Coy, 1849). To understand the nature of the association, a qualitative and quantitative study of the association is conducted on newly examined material (161 lobsters) looking at prevalence, density and abundance of the infestation (per anatomical region of the lobsters). Angularities and flat surface of exoskeletons were also evaluated. The distribution of the bivalves on both sides of the crustaceans (60% of the colonized lobsters), their preservation and their downward growth orientation suggests no post-mortem attachment of the mollusks. Hence, the association may be ascribed to a true palaeosymbiosis between these organisms. The non-homogeneous distribution of bivalves, that is to say an important colonization of the angular ridges of the carapace, is interpreted as selected sites by the mollusks for larval fixation, and may indicate possible half-burrowing posture of lobsters. This palaeosymbiosis has no modern equivalent, as cemented bivalve shells have never been reported on any population of decapod crustaceans. This fossil association may be ascribed to a local Aptian palaeoenvironment comprising swarming spats of anomiid bivalves.

Crayfish Burrows From Maastrichtian Cretaceous Alaska Suggest PaleoTemperature Range Between -6 C to 28C

Crayfish burrows from the latest Cretaceous lower Cantwell Formation (Denali National Park, Alaska): Their morphology and paleoclimatic significance

Authors:

Fiorillo et al

Abstract:

Latest Cretaceous strata of the lower Cantwell Formation, Denali National Park, central Alaska Range, contain an abundance of megafloral remains and invertebrate and vertebrate trace fossils. Though dominated by herbivorous dinosaur footprints, the abundance and diversity of fossil bird tracks are unique. We present newly discovered crayfish burrows from several areas along a 50 km transect with Denali National Park. Most crayfish burrows from the lower Cantwell Formation are preserved only in cross-section and range from approximately 5–10 cm in diameter. Where preserved in full relief and terminations present, burrow depth is generally less than 50 cm. Burrow morphology is similar to burrow morphology of modern freshwater crayfish (Cambaridae).

The Cantwell Formation fills the Cantwell Basin, a 135 km-long and up to 35 km-wide, east–west trending basin, bracketed by the Hines Creek Fault to the north and the McKinley Fault to the south. Basin fill comprises up to 4000 m of continental deposits, interpreted as braided rivers, alluvial fans, floodplains, swamps, and ponds.

Crayfish burrows provide evidence of water table level, soil moisture fluctuations, as well as insight into mean annual temperatures at the time of deposition of the lower Cantwell Formation, a Late Cretaceous high-latitude paleoecosystem. Despite a relatively high latitudinal setting (~ 71°N paleolatitude), the Late Cretaceous (i.e., Campanian–Maastrichtian) mean annual temperature, based on the distribution of similar present-day crayfish burrows, was more like that of southernmost Ontario, Canada, where the northernmost burrowing crayfish are found today. The burrow depth suggests (1) no permafrost was present, and (2) the phreatic zone was ~ 30–50 cm below the paleo-ground surface. Based on the presence of these crayfish burrows, the paleoclimate is interpreted as humid continental (Köppen scheme), with average summer high temperatures between 25 °C and 28 °C and average winter low temperatures between − 6 °C and 0 °C. These estimates compare somewhat favorably with previous CLAMP estimates of a warm monthly mean temperature of 17.08 +/− 1.6 °C and a cold monthly mean temperature of − 2.31 +/− 1.9 °C.

Crustaceans Just Before the Permian Extinction

Evolution of Crustaceans at the edge of the end-Permian crisis: Ichnonetwork analysis of the fluvial succession of Nurra (Permian–Triassic, Sardinia, Italy)

Authors:

Baucon et al

Abstract:

Decapod crustaceans are among the most efficient ecosystem engineers of the Phanerozoic, but the path that led to their engineering success is poorly known. The Permian–Triassic continental succession of Nurra (early Cisuralian–early Middle Triassic; Sardinia, Italy) sheds light on this obscure subject, because it preserves the oldest (Roadian) fluvial Ophiomorpha and Camborygma, ascribed to ghost shrimps (Decapoda: Axiidea, Gebiidea) and crayfishes (Decapoda: Astacidea, Parastacidea), respectively. These crustacean trace fossils are part of a well-preserved ichnofauna including Arenicolites, Diplocraterion, Helminthoidichnites, Palaeophycus, Planolites, rhizoliths, Skolithos, Spongeliomorpha, Taenidium, Treptichnus, alongside an undetermined tetrapod footprint, helical burrows and Sinusichnus-like traces.

In light of the abundance of crustacean trace fossils, the Cala Viola section (Roadian–Anisian) was selected for ichnonetwork analysis. This novel approach, focusing on the topology of the association relationships of ichnotaxa, revealed six ichnoassociations, i.e., Rhizohaloes, Taenidium/Ophiomorpha, Helminthoidichnites, Palaeophycus, Skolithos and Arenicolites ichnoassociations. In addition, ichnonetwork analysis shown that Camborygma and Ophiomorpha colonised adjacent, partially overlapping fluvial subenvironments, ranging from active fluvial channels to periaquatic overbanks. As the Nurra occurrences are penecontemporaneous of the astacid/thalassinid diversification (Carboniferous–Early Permian) and coeval with the appearance of crayfishes (Middle Permian), fluvial environments played an important role in the evolution of both crayfishes and ghost shrimps. The most parsimonious explanation of the observed scenario is that astacid–thalassinid diversification happened in fluvial environments between the Carboniferous and Early Permian, while ghost shrimps invaded marine environments at the Permian–Triassic boundary. In addition, ichnonetwork analysis revealed that the ichnological system simplified across the Permian–Triassic boundary, accounting for a structured Permian ecosystem and fragmented, stressed habitats during the Early Triassic. This scenario is explained by a progressive drying trend that dramatically changed the hydrological features across the Permian–Triassic boundary. This supports the crucial role of global warming in driving the end-Permian crisis and its prolonged recovery.

Stuffed Full of Shrimp the Middle Triassic Luoping Biota was

Penaeoid Decapoda (Dendrobranchiata) from the Luoping Biota (Middle Triassic) of China: systematics and taphonomic framework

Authors:

Schweitzer et al

Abstract:

Two new genera, Anisaeger and Distaeger, and three new species, Anisaeger brevirostrus, A. spiniferus, and Distaeger prodigiosus, extend the range of the Aegeridae (Dendrobranchiata, Penaeoidea) into the Middle Triassic (Anisian) of China. Seven decapod crustacean species are now known from the Luoping biota of southern China. Morphological features of shrimp that are present but rarely mentioned in the neontological literature are recognized as potentially useful in classifying fossil material, including a diaeresis on the exopod of the uropods and multiarticulate flagellae on pleopods. Unusual taphonomic features of the shrimp include fractured cuticle, preservation in lateral, dorsal, and ventral position, and twisted cephalothoraxes.

Insect & Crustacean Fauna From Miocene Neogene Iceland

Before the ‘Big Chill’: A preliminary overview of arthropods from the middle Miocene of Iceland (Insecta, Crustacea)

Authors:

Woppler et al

Abstract:

Well-preserved arthropods are reported from Miocene sedimentary rocks of the Skarðsströnd-Mókollsdalur (9–8 Ma) and Hreðavatn-Stafholt (7–6 Ma) Formations in Iceland. Fossil remains of terrestrial and/or freshwater animals have rarely been reported from the island before. Here we provide the first overview of the surprisingly rich Tortonian fauna from the Hrútagil locality and additional Messinian-aged trichopteran larval cases from the Stafholt locality. The Hrútagil fauna includes representatives of Cladocera (Crustacea: Branchiopoda) and seven insect orders, including several morphotypes of the orders Plecoptera, Dermaptera, Hemiptera (Cercopoidea, Aphididae), Coleoptera, Hymenoptera, Trichoptera (Drusinae), and Diptera (Bibionidae). Previous studies on the Miocene of Iceland have been based principally on pollen analysis and the macrobotanical record with little attention paid to other aspects of the island’s palaeontology. This study provides the first comprehensive systematic description of Miocene arthropods from the northern North Atlantic region and offers the opportunity for a rare glimpse into the late Cenozoic arthropod fauna of Iceland in the context of transatlantic migration and palaeobiogeography and the onset of major global cooling events.

An Eucrustacean Recovered From the Cambrian Orsten

A eucrustacean from the Cambrian ‘Orsten’ of Sweden with epipods and a maxillary excretory opening

Authors:

Waloszek et al

Abstract:

The Cambrian species Paulinecaris siveterae n. gen. n. sp., known from two trunk fragments, represents the first record of epipods (serving as gills and osmoregulatory structures) in a crustacean from the Swedish ‘Orsten’. Moreover, it is the first report of the maxillary excretory opening of a crustacean based on Cambrian material of ‘Orsten’-type preservation. One specimen comprises the maxillary segment with an appendage and several thoracic segments with parts of their limbs; a second specimen is a fragment possibly of a more posterior part of the trunk. As in other known small eucrustaceans, the tergites of the new species lack prominent tergopleurae, so that the limbs insert directly ventral to the tergal margins. Limb preservation includes the maxilla and several thoracopods, all possessing a prominent, fleshy basipod with six setose endites along their median rim distally to the proximal endite. The presence of long and prominent limbs of P. siveterae suggests that it had good swimming ability, while the slight C-like curvature of their basal limb part, basipod, indicates involvement of the limbs also in so-called ‘sucking chambers’ for suspension feeding coupled with locomotion. The estimated total length of P. siveterae, 2–3 mm, is comparable to that of extant cephalocarids, but its appendages are twice as long and wide. The limbs of P. siveterae also differ in size and armature from extant eucrustaceans as well as early representatives of this group known from the ‘Orsten’ assemblages. The general morphology of the limbs, for example in having a fleshy and C-shaped basipod with several setae-bearing endites medially, identifies P. siveterae as an entomostracan eucrustacean, but a lack of further details precludes its affinity with any of the in-group taxa. Three epipods on the outer edge of the basipod, as in P. siveterae, are also known from the Cambrian eucrustacean Yicaris dianensis from China and early ontogenetic stages of extant fairy shrimps (Anostraca); their adult stages have two epipods. This hints at an original number of three epipods in the ground pattern of Entomostraca, but some uncertainty remains with regard to the eucrustacean ground pattern because Malacostraca possess a maximum number of two.

Crustaceans Suffered as Much as Coral Reefs Between the Permian Extinction to the Tithonian Jurassic

Many ancient crustaceans went extinct following a massive collapse of reefs across the planet, and new University of Florida research suggests modern species living in rapidly declining reef habitats may now be at risk.

Available online and scheduled to appear in the November issue of Geology, the study shows a direct correlation between the amount of prehistoric reefs and the number of decapod crustaceans, a group that includes shrimp, crab and lobster. The decline of modern reefs due to natural and human-influenced changes also could be detrimental, causing a probable decrease in the biodiversity of crustaceans, which serve as a vital food source for humans and marine animals such as fish, said lead author Adiël Klompmaker, a postdoctoral researcher at the Florida Museum of Natural History on the UF campus who started the study at Kent State University.

“We estimate that earth’s decapod crustacean species biodiversity plummeted by more than 50 percent during a sharp decline of reefs nearly 150 million years ago, which was marked by the extinction of 80 percent of crabs,” Klompmaker said. “If reefs continue to decline at the current rate during this century, then a few thousand species of decapods are in real danger. They may adapt to a new environment without reefs, migrate to entirely new environments or, more likely, go extinct.”

Some scientists predict as much as 20 percent of the world’s reefs may collapse within 40 years, with a much higher percentage affected by the end of the century due to natural and human-influenced changes such as ocean acidification, diseases and coral bleaching.

The study is the first comprehensive examination of the rise of decapod crustaceans in the fossil record. Researchers created a database of fossils from the Mesozoic Era, 252 million to 66 million years ago, from literature records based on museum specimens worldwide. The data included 110 families, 378 genera and 1,298 species. They examined the patterns of diversity and found an increase in the number of decapod species was influenced by the abundance of reefs, largely due to the role of reefs as a provider of shelter and foraging. Researchers call this period the “Mesozoic decapod revolution” because of the 300-fold increase in species diversity compared with the previous period and the appearance and rapid evolution of crabs.

Compiling information about crustaceans on this scale has historically been a challenge for researchers because most decapods possess a fragile and weakly calcified exoskeleton that does not fossilize well.

“Only a scant fraction of decapod crustaceans is preserved in rocks, so their fossil record is limited,” said study co-author Michal Kowalewski, curator of invertebrate paleontology at the Florida Museum. “But, thanks to efforts of paleontologists many of those rare fossils have been documented all around the world, finally giving us a chance to look at their evolutionary history in a more rigorous, quantitative way.”

“This new work builds a good case for the role of reefs in promoting the evolutionary diversification of crustaceans,” said David Jablonski, a paleontologist in the department of geophysical sciences at the University of Chicago who was not involved in the study. “We have to take their argument for the flipside of that story very seriously. The positive relation between reefs and crustaceans implies that the damage caused to reefs by human activities — from overfishing to ocean acidification — is likely to have cascading consequences for associated groups, including crustaceans.”

link.

Cambrian Ostracod Found...With Soft Tissues Preserved

A geologist from the University of Leicester is part of a team that has uncovered an ancient water flea-like creature from 425 million years ago – only the third of its kind ever to be discovered in ancient rocks.

Professor David Siveter, of the Department of Geology at the University of Leicester worked with Professor Derek Siveter at the Oxford University Museum of Natural History, Professor Derek Briggs at Yale University USA and Dr Mark Sutton at Imperial College to make the rare discovery.

The specimen, which was found in rocks in Herefordshire, represents a new species of ostracod, and has been named Nasunaris flata. Like water-fleas and shrimps, ostracods belong to the group of animals called Crustacea. The find is important because the fossil has been found with its soft parts preserved inside the shell.

Today its descendents are common, and inhabit ponds, rivers and lakes and many parts of the seas and oceans, having first appeared on Earth about 500 million years ago.

No time...

Insect Origins Revealed?

Since the dawn of the biological sciences, mankind has struggled to comprehend the relationships among the major groups of "jointed-legged" animals — the arthropods. Now, a team of researchers, including Dr. Joel Martin and Dr. Regina Wetzer from the Natural History Museum of Los Angeles County (NHM), has finished a completely new analysis of the evolutionary relationships among the arthropods, answering many questions that defied previous attempts to unravel how these creatures were connected. Their study is scheduled for publication in the journal Nature on Feb. 24.

Now, for the first time, science has a solid grasp of what those relationships are, and a framework upon which to build. The new study makes a major contribution to our understanding of the nature and origins of the planet's biodiversity. The paper's other researchers are Jerome C. Regier, Andreas Zwick and April Hussey from the University of Maryland Biotechnology Institute; Jeffrey W. Shultz of the University of Maryland's Department of Entomology; and Bernard Ball and Clifford W. Cunningham from Duke University's Department of Biology.

There are millions of distinct species of arthropods, including all the insects, crustaceans, millipedes, centipedes, spiders, and a host of other animals, all united by having a hard external shell and jointed legs. They are by far the most numerous, and most diverse, of all creatures on Earth — in terms of the sheer number of species, no other group comes close. They make up perhaps 1.6 million of the estimated 1.8 to 1.9 million described species, dominating the planet in number, biomass, and diversity.

The economic aspects of arthropods are also overwhelming. From seafood industries worth billions of dollars annually to the world's economy, to the importance of insects as pollinators of ornamental and agriculturally important crops, to the medical role played by arthropods (e.g. as disease vectors and parasites), to biological control of introduced species, to their role in every known food web, to toxicology and biopharmaceuticals, arthropods are by far the planet's most important group of animals.

"We've never really known how arthropods, the most successful animals on Earth, evolved into the diversity we see today," said research scientist and co-author Dr. Regina Wetzer. "For me, what makes this study really exciting is getting such a solid understanding of how these animals are related, so that now we can better understand how they evolved."

Because of their amazing diversity, deciphering the evolutionary history and relationships among the major subgroups of arthropods has proven difficult. Scientists have tried using various combinations of features, in recent years including DNA sequences, to try to understand which groups are related through common ancestors. To date, those attempts have been stymied by the sheer number of species and wild shape variations between the various groups.

One of the most important results of this new study is support for the hypothesis that the insects evolved from a group of crustaceans. So flies, honeybees, ants, and crickets all branched off the arthropod family tree from within the lineage that gave rise to today's crabs, shrimp, and lobsters. Another important finding is that the "Chelicerata" (a group that includes the spiders, scorpions, ticks, and mites) branched off very early, earlier than the millipedes, centipedes, crustaceans, and insects. That means that the spiders, for example, are more distantly related to the insects than many researchers previously thought.

This team approached the problem of illuminating the arthropod family tree by using genetic data (DNA sequences) obtained from 75 species carefully selected to sample the range of arthropod diversity. Many previous analyses were based on the sequences of a handful of genes. The researchers in this study, knowing the daunting diversity they faced, used DNA sequence information from as many genes as they could. In the end, they were able to apply data from 62 protein-coding genes to the problem, leading to an extremely well-supported analysis.

Slightly overblown press release, but still interesting.

Crustacean Parasite?

First identified in 1899, y-larvae have been one of the greatest zoological mysteries for over a century. No one has ever found an adult of these puzzling crustaceans, despite the plethora of these larvae in plankton, leading generations of marine zoologists to wonder just what y- larvae grow up to be. A study published in BioMed Central’s open access journal, BMC Biology, reports the transformation of the larvae into a previously unseen, wholly un-crustacean-like, parasitic form.

Y larvae, or facetotectans, are found amongst marine plankton in oceans from the poles to the tropics. In coral reef areas they occur dizzying diversity, even though they are ubiquitous and similar to the larvae of barnacles, not one adult y-organism has been identified in over 100 years of considerable searching.

“Facetotectans are the only crustacean group with a taxonomy based solely on larval stages”, say Henrik Glenner and Jens Hoeg (University of Copenhagen) and colleagues from Japan “but the great species diversity indicates that the adults play an important ecological role.” Supported by the Carlsberg Foundation in Denmark and the Lake Biwa Museum in Japan, the study authors collected the study authors collected over 40 species of y larvae from one site at Sesoko Island near Okinawa, Japan, and exposed many of them to a crustacean moulting-hormone to encourage them to mature. The free-swimming y-larvae shed their articulated exoskeleton, and a simple, slug- like, pulsing mass of cells emerged.

The authors explain “The musculature and compound eyes that you might expect to see in adult crustaceans were in a state of degeneration, and from our observations of the live, and also preserved specimens, we conclude that the adults of these larvae must be parasites – but of what we do not know.”

And just when you thought life couldn't through a weirder one at you...

ew.