62 research outputs found
Revision of <i>"Balaena" belgica</i> reveals a new right whale species, the possible ancestry of the northern right whale, <i>Eubalaena glacialis</i>, and the ages of divergence for the living right whale species
In 1941, Abel established Balaena belgica based on a series of fused cervical vertebrae and citing other cranial fragments from the late Neogene of the Antwerp harbor (northern Belgium). Later, Plisnier-Ladame & Quinet (1969) added a neurocranium and other skeletal remains from the same area to this species. Recently, the neurocranium was re-assigned to the genus Eubalaena thanks to newer phylogenetic analyses. Here, a new description is provided of materials previously assigned to âBalaenaâ belgica together with taxonomic revisions. Our work suggests that the cervical complex originally designated as the type of âBalaenaâ belgica is too poorly preserved to be used as such and is assigned to Balaenidae gen. et sp. indet., thus making âBalaenaâ belgica a nomen dubium. In addition to the neurocranium, the other remains consist in a fragment of maxilla assigned to Balaenidae gen. et sp. indet. and in a humerus assigned to Eubalaena sp. Discovered in the Kruisschans Sands Member of the Lillo Formation (3.2â2.8 Ma, Piacenzian, Late Pliocene), the neurocranium is designated as the holotype of the new species Eubalaena ianitrix. Our phylogenetic analysis supports a sister-group relationship of Eubalaena ianitrix and Eubalaena glacialis, and helps constraining the ages of origin for balaenid clades. Ecological and phylogenetic data suggest that Eubalaena ianitrix may represent the direct ancestor of Eubalaena glacialis, the latter having evolved through phyletic transformation including body size increase during the temperature decline of the Late Pliocene
A Pliocene gray whale (Eschrichtius sp.) from the eastern North Atlantic
The gray whale Eschrichtius robustus, the only living member of the eschrichtiid lineage, currently inhabits only the North Pacific. Interestingly, however, the holotypes of both E. robustus and the late Miocene Archaeschrichtius ruggieroi (the oldest known eschrichtiid species) come from the North Atlantic and the Mediterranean, respectively. Here we describe a partial mysticete mandible from the Pliocene (3.71â2.76 Ma) of Belgium (Eastern North Atlantic). This new fossil displays a combination of morphological features that makes it nearly identical to modern E. robustus. Nevertheless, given its incomplete nature, the studied specimen is here identified in open nomenclature as belonging to Eschrichtius sp. The recognition of such an early record of Eschrichtius in the North Atlantic suggests that this genus developed a circum-Northern Hemisphere distribution not later than in Pliocene times, thus complicating our understanding of its origin, evolutionary history, and palaeobiogeographic patterns
Stratigraphy of an Early-Middle Miocene sequence near Antwerp in northern Belgium (southern North Sea Basin)
The lithostratigraphy and biostratigraphy of a temporary outcrop in the Antwerp area is described. The deposits can be attributed to the Kiel Sands and the Antwerpen Sands members, both belonging to the Lower and Middle Miocene Berchem Formation. Invertebrate and vertebrate macrofossils are abundantly present. The molluscan fauna compares well to former findings in the Antwerpen Sands Member. It can be concluded that the studied sequence is continuously present in the Antwerp area, and thickens in a northward direction. The study of the marine mammal fauna shows that eurhinodelphinids are the most common fossil odontocete (toothed-bearing cetaceans) in the Antwerpen Sands Member, associated here with kentriodontine, physeteroid, squalodontid, mysticete (baleen whales) and pinniped (seals) fragmentary remains. Both the molluscan fauna and the organic-walled palynomorphs indicate for the Antwerpen Sands Member deposition in a neritic, energetic environment, which shallowed upwards. The dinoflagellate cysts indicate that the Antwerpen Sands Member was deposited during late Burdigalian to Langhian times
Geology and palaeontology of a temporary exposure of the late Miocene Deurne sand in Antwerpen (N.Belgium)
A section of 6.10 m through the Deurne Sand Member (Diest Formation, Late Miocene) in Antwerpen (Antwerp) is described, which has been observed during the construction works of a new hospital building in the southern part of Deurne, and here called âMiddelares Hospital Sectionâ after that location. This temporary outcrop section can well be correlated with a similar one which was outcropping some 35 years ago, and was located at some 1.5 km to the NE. It was studied in detail by De Meuter et al. (1967), who called it the âBorgerhout-Rivierenhof VII B.R.â section. Since that section was the most relevant of the previously described sections in the Deurne Sand Member, it is here suggested to designate that section as stratotype for the member. Part of the fossil content, mainly the macrofossils (Brachiopoda, Mollusca, Ostracoda, Thoracica, Pisces, Reptilia and Mammalia) is listed. Two species of Terebratulidae (Pliothyrina sowerbyana (Nyst, 1843) and Terebratula cf. ampulla Brocchi, 1814) were recognized. The Mollusca are represented by 24 taxa, of which the Pectinidae are the most common. One undescribed ostracod taxon (Thaerocythere sp.) is restricted to the Deurne Sands and can be considered a stratigraphic marker for this member. Fossil Lepadomorpha are recorded for the first time from the Belgian Late Miocene. The Squalus sp. from the Deurne Sands closely resembles the Squalus sp. from the Gramian of Denmark. Preliminary data about a fairly complete skeleton of a Mysticete whale, probably belonging to the genus Plesiocetus Van Beneden (in Van Beneden & Gervais, 1880) are given. The recovered specimen of Ziphirostrum is characteristic of Z. laevigatum and is probably different from Z. belgicus. The molluscan fauna seems to point to a shallow environment with swiftly changing currents, moving sand bars or megaripples subjected to tidal currents. Palaeoclimatological data cannot be deducted from the fossils encountered
A leatherback turtle (Testudines, Dermochelyidae) from the Miocene of the Westerschelde, the Netherlands
The Westerschelde Estuary in The Netherlands is known for its rich vertebrate fossil content. In a recent trawling campaign aimed at sampling a late Miocene marine vertebrate assemblage, over 5000 specimens were retrieved, all currently stored in the Natuurhistorisch Museum Rotterdam. One specimen is a well preserved fragment of a dermochelyid sea-turtle carapace. The Westerschelde specimen is an addition to the scant hypodigm of dermochelyids from the Miocene North Sea. The carapace fragment is described and identified as Psephophorus polygonus. The various secondary marks present on the fragment are suggestive of both predatory and scavenging origin. Based on the assumption that P. polygonus had a similar carapace structure as recent D. coriacea, the minimal size of the complete carapace is estimated to have been 168 x 126 cm. Furthermore, based on the physical traits of the Westerschelde specimen and a reexamination of P. polygonus specimens, including the neotype stored at the Naturhistorisches Museum Wien (Austria), it is argued that previously assigned characteristics cannot be used as discriminative taxonomic properties of dermochelyids in general, and of P. polygonus in particular. An improved cladistic analysis on dermochelyids is performed based on previously defined and new taxonomic characters. Using this analysis it is argued that Psephophorus calvertensis is a junior synonym of P. polygonus. Hence, a new diagnosis of Psephophorus polygonus is defined. The âadditionâ of P. calvertensis to the species P. polygonus confirms its presence on both sides of the Atlantic Ocean. Therefore, we suggest P. polygonus to have had a cosmopolitan distribution, similar to the extant species Dermochelys coriacea
A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the western Desert of Egypt
A new fossil site at Minqar Tibaghbagh, east of Siwa, in the Egyptian Western Desert is described. This represents the first place in Egypt outside the Fayum Depression yielding Paleogene, terrestrial mammals. Initial studies indicate the presence of palaeomastodonts, hyracoids, and anthracotheres, presumably early Oligocene in age. As only surface prospecting has been performed, more taxa will almost certainly be discovered in future investigations here and probably also elsewhere in the surroundings. A comparison is made with the most important contemporaneous sites in Libya and Egypt that yield terrestrial mammal remains. The selachian fauna from a higher level in the section confirms the Paleogene age of the subjacent strata. It is compared with selachians faunas from the early Oligocene Eastern Tethys Ocean at other places (the Fayum Depression in Egypt, and sites in Oman and Pakistan), and differs from these sites in being fully marine. Contrary to earlier studies, the open marine mudstones of the Dabaâa Formation at Minqar Tibaghbagh are overlain by Paleogene marine sediments of most probably early Oligocene age and not early Miocene marine sediments as previously reported. These strata represent not only a new site with great potential for future finds, but also allows for biostratigraphic correlation
The dynamics of human body weight change
An imbalance between energy intake and energy expenditure will lead to a
change in body weight (mass) and body composition (fat and lean masses). A
quantitative understanding of the processes involved, which currently remains
lacking, will be useful in determining the etiology and treatment of obesity
and other conditions resulting from prolonged energy imbalance. Here, we show
that the long-term dynamics of human weight change can be captured by a
mathematical model of the macronutrient flux balances and all previous models
are special cases of this model. We show that the generic dynamical behavior of
body composition for a clamped diet can be divided into two classes. In the
first class, the body composition and mass are determined uniquely. In the
second class, the body composition can exist at an infinite number of possible
states. Surprisingly, perturbations of dietary energy intake or energy
expenditure can give identical responses in both model classes and existing
data are insufficient to distinguish between these two possibilities. However,
this distinction is important for the efficacy of clinical interventions that
alter body composition and mass
Side channel analysis of some hash based MACs:A response to SHA-3 requirements
The forthcoming NIST's Advanced Hash Standard (AHS) competition to select SHA-3 hash function requires that each candidate hash function submission must have at least one construction to support FIPS 198 HMAC application. As part of its evaluation, NIST is aiming to select either a candidate hash function which is more resistant to known side channel attacks (SCA) when plugged into HMAC, or that has an alternative MAC mode which is more resistant to known SCA than the other submitted alternatives. In response to this, we perform differential power analysis (DPA) on the possible smart card implementations of some of the recently proposed MAC alternatives to NMAC (a fully analyzed variant of HMAC) and HMAC algorithms and NMAC/HMAC versions of some recently proposed hash and compression function modes. We show that the recently proposed BNMAC and KMDP MAC schemes are even weaker than NMAC/HMAC against the DPA attacks, whereas multi-lane NMAC, EMD MAC and the keyed wide-pipe hash have similar security to NMAC against the DPA attacks. Our DPA attacks do not work on the NMAC setting of MDC-2, Grindahl and MAME compression functions. This talk outlines our results
Taxonomic revision of <i>Isocetus depauwi</i> (Mammalia, Cetacea, Mysticeti) and the phylogenetic relationships of archaic 'cetothere' Mysticetes
The taxonomic revision of Isocetus depauwi Van Beneden, 1880 was carried out through the description of a number of specimens assigned to this species by Van Beneden and Abel in the last decades of the 19th and the early decades of the 20th centuries. After detailed comparisons with the published record of archaic mysticetes, the genus and species are considered valid despite the incompleteness and poor preservation of the material. Diagnostic features are found in the morphology of the mandibular condyle, the angular process of the dentary and the thoracic vertebrae. The new species Parietobalaena campiniana is established based on a partial skeleton, including most of the skull and ear bones, previously assigned to Isocetus depauwi by Abel. Parietobalaena campiniana is described and compared in detail, and its phylogenetic relationships are assessed by a new large-scale cladistic analysis of 246 morphological characters scored for 46 taxa. The results support a basal position of the genus Parietobalaena in the radiation of Miocene âcetotheresâ, the monophyly of Balaenoidea (Neobalaenidae and Balaenidae), Balaenopteroidea (Eschrichtiidae and Balaenopteridae), and Cetotheriidae and the paraphyly of âcetotheresâs.l. The new superfamily Thalassotherii is established based on high bootstrap support and a number of morphological characters; Thalassotherii includes Balaenopteridae, Eschrichtiidae, Cetotheriidae and the basal âcetothereâ mysticetes with the exclusion of Balaenoidea, Eomysticetoidea and toothed mysticetes
- âŠ