A new tube-builder hydractinian, symbiotic with hermit crabs, from the Cretaceous of Antarctica

1994 ◽  
Vol 68 (6) ◽  
pp. 1169-1182 ◽  
Author(s):  
Eduardo B. Olivero ◽  
Maria B. Aguirre-Urreta
Keyword(s):  
Functional Analysis ◽  
Water Depth ◽  
Deep Water ◽  
Upper Cretaceous ◽  
Fine Sand ◽  
Hermit Crabs ◽  
Spiral Tube ◽  
Fine Grained ◽  
Depositional Settings ◽  
First Time

An Upper Cretaceous (early Maastrichtian) tube-building hydractinian (Psammoactinia antarctica n. gen. and sp.) from Sanctuary Cliffs, Snow Hill Island, believed to live in association with hermit crabs, is described for the first time from Antarctica. Psammoactinia forms thick, concentric, globular colonies that encrust gastropod shells and extend the shell aperture by forming an open spiral tube. The colony consists of concentric layers with chambers and pillars made of silt and very fine sand grains agglutinated by collophane, which is interpreted as a diagenetic modification of an original chitinous phosphatic material. On the basis of the additional finding of isolated claws of pagurid crabs, assigned to Paguristes sp., the functional analysis of the hydractinian structure, and a comparison with modern and fossil analogous structures it is concluded that the peculiar hydractinian tube is a carcinoecium that housed a symbiotic hermit crab.Paleoenvironmental and paleoecological inferences suggest that the Psammoactinia–Paguristes association is mainly controlled by a fine-grained substrate and by a lack of abundant gastropod shells of different sizes. These factors do not necessarily correlate with absolute water depth, and favorable environments could include either offshore, relatively deep water or shallow restricted depositional settings.

scholarly journals High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)

2010 ◽  
Vol 61 (1) ◽  
pp. 29-38
Author(s):  
Damir Bucković ◽  
Maja Martinuš ◽  
Duje Kukoč ◽  
Blanka Tešović ◽  
Ivan Gušić
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
High Frequency ◽  
Upper Cretaceous ◽  
Distal Part ◽  
Preferential Orientation ◽  
Sea Level Changes ◽  
Carbonate Production ◽  
Fine Grained ◽  
Platform Margin

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)The upper part of the Middle Coniacian/Santonian-Middle Campanian deep-water Dol Formation of the island of Brač is composed of countless fine-grained allodapic intercalations deposited in an intraplatform trough. Within the studied section 13 beds can be distinguished, each defined by its lower part built up of dark grey limestone with abundance of branched, horizontally to subhorizontally oriented burrows, and the upper part, in which the light grey to white limestone contains larger burrows, rarely branched, showing no preferential orientation. The lower, dark grey, intensively bioturbated levels are interpreted as intervals formed during high-frequency sea-level highstands, while the upper, light grey-to-white levels are interpreted as intervals formed during the high-frequency sea-level lowstands. Cyclic alternation of these two intervals within the fine-grained allodapic beds is interpreted as the interaction between the amount of carbonate production on the platform margin and the periodicity and intensity of shedding and deposition in the distal part of toe-of-slope environment, which is governed by Milankovitch-band high frequency sea-level changes.

First reports of deep-water hermit crabs Parapagurus Smith, 1879 (Decapoda, Parapaguridae) and coelenterate associates from the Mid-Atlantic Ridge and South Atlantic

Crustaceana ◽  
2012 ◽  
Vol 85 (4-5) ◽  
pp. 591-600 ◽  
Author(s):  
Irene Cardoso ◽  
Rafael Lemaitre
Keyword(s):  
Deep Water ◽  
Deep Sea ◽  
South Atlantic ◽  
Open Ocean ◽  
Hermit Crabs ◽  
The South ◽  
Mid Atlantic Ridge ◽  
Seamount Chain ◽  
First Time ◽  
Important Habitat

Three species of deep water hermit crabs of the genus Parapagurus Smith, 1879, family Parapaguridae, were collected in the South Atlantic during studies of the fauna and ecology of the Mid-Atlantic Ridge, a seamount chain that is an important habitat, feeding ground, and site of reproduction for many open ocean and deep-sea species. The three species collected, P. abyssorum (Filhol, 1885), P. nudus (A. Milne-Edwards, 1891), and P. pilosimanus Smith, 1879, are known to range broadly in the Atlantic, but only one, P. pilosimanus, was previously reported from the South Atlantic. Thus, P. abyssorum and P. nudus are reported for the first time from the Mid-Atlantic Ridge and the South Atlantic. These three species live in association with zoanthids or actinians that produce carcinoecia and serve as housing. The carcinoecia found with the specimens are also reported.

Northeast Pacific Upper Cretaceous and Paleocene Glycymeridid Bivalves

2010 ◽  
Vol 84 (5) ◽  
pp. 895-917 ◽  
Author(s):  
Richard L. Squires
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
New Combination ◽  
Marine Waters ◽  
Shallow Marine ◽  
Fine Grained ◽  
Northeast Pacific ◽  
Siliciclastic Sediments ◽  
First Time ◽  
Warm Temperate

The Late Cretaceous to late Paleocene record of glycymeridid bivalves in the region extending from the Alaska Peninsula, southward to Baja California, Mexico is studied in detail for the first time. Glycymeris pacifica (Anderson, 1902), of late Cenomanian to late Turonian age, is the earliest known glycymeridid in the study area. Very locally, it is found with the middle to late Turonian Glycymeris yoloensis n. sp. The latter apparently represents some intermediate state between genus Glycymeris da Costa, 1778 and genus Glycymerita Finlay and Marwick, 1937. In the study area, Glycymerita is represented by Glycymerita veatchii (Gabb, 1864), middle to late Turonian to late Campanian; Glycymerita banosensis (Anderson, 1958) new combination, late Campanian to latest Maastrichtian; Glycymerita aleuta n. sp., known only from Alaska and of early Maastrichtian age; and Glycymerita major (Stanton, 1896) new combination, Selandian to Thanetian. All the studied species lived in warm-temperate, shallow-marine waters and were shallow burrowers in fine-grained siliciclastic sediments. Variability in morphology is common in sizeable populations of the various species, especially Glycymerita veatchii, which increased nearly fivefold in size during its 19.5 million-year-long range and culminated in shells up to 84 mm in length.

Anatomy and functional morphology of the largest marine reptile known, Mosasaurus hoffmanni (Mosasauridae, Reptilia) from the Upper Cretaceous, Upper Maastrichtian of The Netherlands

1995 ◽  
Vol 347 (1320) ◽  
pp. 155-180 ◽  
Keyword(s):  
Functional Analysis ◽  
The Netherlands ◽  
Functional Morphology ◽  
Upper Cretaceous ◽  
Lower Jaw ◽  
Olfactory Organs ◽  
Marine Reptile ◽  
Four Bar Linkage ◽  
First Time ◽  
Upper Maastrichtian

Mosasaurus hoffmanni , one of the latest known mosasaurs, comes from the Upper Maastrichtian, Upper Cretaceous Chalk of The Netherlands. Although the first specimen was discovered over 200 years ago, it is here fully described for the first time to provide detailed insights into its anatomy, functional morphology and evolution. Many characters of the skull show that M. hoffmanni was among the most advanced mosasaurs. The skull is robustly constructed and is the least kinetic in the Mosasauridae and, with a tightly assembled palatal complex, provided greater cranial stability in this large-headed mosasaur. The cranial musculature is highly modified. The four-bar linkage system of lizards and early mosasaurs is non-functional in M. hoffmanni . The elements of the lower jaw are also more tightly united than in other mosasaurs. Tooth crowns are divided into several distinct, unique cutting surfaces or prisms. A functional analysis of the marginal teeth shows that they are particularly adapted to powerful bite forces although pterygoidal teeth are small and reduced in importance in ratchet feeding. Moderately large orbits and poorly developed olfactory organs suggest that Mosasaurus hoffmanni was a surface-swimming animal. A relatively lower level of binocular vision than in some other mosasaurs may indicate a somewhat uncomplicated habitat. Geological and palaeontological evidence indicates that M. hoffmanni lived in fairly deep nearshore waters of 40—50 m depth, with changing temperatures and rich vertebrate and invertebrate life. Several severely broken and healed mandibles suggest either a violent lifestyle in predation or in fighting.

scholarly journals Coniacian–Santonian Radiolaria from the Upper Cretaceous of Bornholm, Denmark: A preliminary investigation

2005 ◽  
Vol 52 ◽  
pp. 141-158
Author(s):  
Stephen R. Packer ◽  
Malcolm B. Hart
Keyword(s):  
Late Cretaceous ◽  
Water Depth ◽  
Upper Cretaceous ◽  
Preliminary Investigation ◽  
Poor Recovery ◽  
Relative Water ◽  
Maximum Water ◽  
Abundance And Diversity ◽  
First Time

A moderately diverse fauna of Late Cretaceous Radiolaria are described for the first time from the Arnager Limestone and Bavnodde Greensand formations exposed on the island of Bornholm (Denmark). Our preliminary investigation suggests that the fauna from the Arnager Limestone Formation is relatively abundant and is assigned to the Orbiculiforma vacaensis Subzone (Alievium praegallowayi Zone) of Coniacian age. Relatively poor recovery from the Bavnodde Greensand Formation precludes assignment to the zonation scheme of Pessagno, although, the radiolarian taxa present indicate that the formation can be no younger than Santonian. The ages given for both formations by the radiolarian faunas compare favourably with published macrofossil and microfossil data. The radiolarian faunas described are of moderate abundance and diversity when compared to contemporaneous faunas described elsewhere, particularly the Tethyan area. Maximum radiolarian abundance and diversity is reached in the middle of the Arnager Limestone Formation equating to a level of maximum water depth from the foraminiferal data. A decline in radiolarian recovery is recognised into the Bavnodde Greensand Formation and is associated with a reduction in relative water depth to inner and (?)middle shelf conditions, as indicated by foraminiferal data.

ANALYSIS OF THE FUNCTIONING OF MARINE ECOSYSTEMS ON CHANGING THE PARAMETERS OF THE BIOLUMINESCENCE FIELD ON THE CRIMEAN BLACK SEA SHELF

2017 ◽  
Author(s):  
Svetlana Rubtsova ◽  
Svetlana Rubtsova ◽  
Natalya Lyamina ◽  
Natalya Lyamina ◽  
Aleksey Lyamin ◽  
...  
Keyword(s):  
Black Sea ◽  
Field Intensity ◽  
Deep Water ◽  
Coastal Waters ◽  
Integrated Management ◽  
Abiotic Factors ◽  
Environmental Safety ◽  
The Black Sea ◽  
Intensity Increase ◽  
First Time

The concept of a new approach to environmental assessment is offered in the system of integrated management of the resource and environmental safety of the coastal area of the Black Sea. The studies of the season and daily changeability in the bioluminescence field in the Sevastopol coastal waters has been conducted. For the first time considerable differences in the bioluminescence field seasonal changes in the surface and deep water layers and the reasons conditioning this phenomenon have been shown, using a method of multidimensional statistical analysis. The bioluminescence field vertical profile change in the Black sea coastal waters in the autumn period at night has been studied. It has been shown that according to the character of bioluminescence parameters dynamics a water column can be divided into layers: upper (0 – 35 m) and deep water (36 – 60 m). It has been revealed that life rhythms of the plankton community are the main reason for the bioluminescence field intensity variability. It has been revealed that 14-hour periodicity of the bioluminescence field is related to the changes in light and its variations with 2,5…4,5 hours are conditioned by planktonts endogenous daily rhythms. And here biotic factors effect mostly periodicity of the bioluminescence field intensity increase and fall down at the dark time of the day. Abiotic factors are of less importance in circadian rhythmic of the bioluminescence field in the neritic zone.

First description of the male of Cretaconiopteryx grandis Liu & Lu, 2017 (Neuroptera: Coniopterygidae) from the Cretaceous Burmese amber

Zootaxa ◽  
2019 ◽  
Vol 4674 (4) ◽  
pp. 482-490 ◽  
Author(s):  
HONGYU LI ◽  
BO WANG ◽  
XINGYUE LIU
Keyword(s):  
Male Genitalia ◽  
Upper Cretaceous ◽  
Sister Group ◽  
Sister Group Relationship ◽  
Burmese Amber ◽  
Representative Species ◽  
First Time

The male of Cretaconiopteryx grandis Liu & Lu, 2017, which is the only representative species of the extinct dustywing subfamily Cretaconiopteryginae, is described for the first time from the Upper Cretaceous Burmese amber. The male genitalia, well preserved in the examined specimen, show a number of plesiomorphic characters, which support the sister group relationship between Coniopterygidae and the rest of extant lacewing families. 

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