Prehistoric Guinea Pigs from Egypt

A study recently published by the Proceedings of the National Academy of Sciences describes how modern day representatives of the Phiomorpha and Caviomorpha groups diverged approximately 37 million years ago.

The phylogeny detailed in the article was derived through combination of biogeographical, genetic and fossil evidence, and serves to demonstrate that the Caviomorpha, a group that includes modern-day guinea pigs, separated from the Phiomorpha during the early Eocene epoch between 34 and 40 million years ago.

Prior to divergence, both groups were bound by the rodent infraorder Hystricognathi and were restricted to Afro-Arabia. In sync with the rise of modern mammals during the Eocene, members of the Cavimorpha parted ways with the Phiomorpha and emmigrated to South America, possibly by rafting or other chance dispersal event. The Phiomorpha remained behind in Afro-Arabia where they radiated into a variety of genera, including the extant genus Thryonomys – commonly known as cane rats.

Key to the study’s finding was morphological examination of fossil assemblages excavated from the Fayum Depression of northeast Egypt. The mandibular and maxillary fossils recovered from the site revealed a mixture of both primitive and derived features. This fossil data was amalgamated with independently calculated genetic estimates to narrow the timing for the early Eocene divergence.


Sallam, H., Seiffert, E., Steiper, M., & Simons, E. (2009). Fossil and molecular evidence constrain scenarios for the early evolutionary and biogeographic history of hystricognathous rodents Proceedings of the National Academy of Sciences, 106 (39), 16722-16727 DOI: 10.1073/pnas.0908702106

Taking a Bite out of Niche Conservatism

In efforts to quash assumptions associated with niche conservatism, scientists from the Florida Museum of Natural History and the New York State Museum have enlisted the teeth of several fossil mammals to better understand the ecology of climate change.

Recently published at PLoS One, the research holds critical the idea that niches remain constant over extended periods of time. This idea, called niche conservatism, essentially holds that niches are highly specialized, ancestrally –linked, relatively inflexible and are therefore exceedingly susceptible to disturbance and rapid degradation in the face of change - particularly climate change.

While biologic response to environmental change is assumed, often such conservatism is overemphasized and is presented in a manner inconsistent with understanding gained through modern ecology and the insights of paleontology, which have both demonstrated incredible plasticity within the Earth’s biota.

Undoubtedly, the changing climate is of great concern and poses tremendous challenges to all organisms, but at the same time life is flexible and extinctions are not entirely unavoidable. As evidence to life’s flexibility, the currently discussed paper uses the testimony of change documented in the isotopic signatures of mammalian tooth enamel to show that the obstacle of climate change has been successfully negotiated in the past. More specifically, glacial-interglacial transitions during the Pliocene and Pleistocene are marked by substantial alterations in plant communities; however the contemporaneous uptake of vegetative food-stuffs by mammals seems to have fluctuated little.

The article is worth a read:
DeSantis, L., Feranec, R., & MacFadden, B. (2009). Effects of Global Warming on Ancient Mammalian Communities and Their Environments PLoS ONE, 4 (6) DOI: 10.1371/journal.pone.0005750


Vertebrates, and in particular mammals, are highly responsive to changes in the environment. Climate fluctuation can lead to an incredible amount of variation in the diet choice, distribution, and even the morphology of vertebrates.

Natural selection is a reflection of the biological and physical environment as transcribed into the genes of flora and fauna; however, the DNA found within living cells functions only as a recipe for ecological fit, the actual ingredients – the building materials - required to construct living tissue are harvested from surrounding chemistry. Because of variability inherit to this chemistry, the isotopic constituents that compose individuals may differ with respect to climate, diet, or a number of other variables.

For example, carbonate apatite - a primary constituent of both skeletal bones and dentition in vertebrates - is incorporated into organisms through diet and water uptake. Some conservationists use the isotopic signatures recovered from this apatite to better decipher the life histories of contemporary species in expectation of aiding in their continued preservation. As a case in point, remains from the world’s largest cavefish (Milyeringa veritas) have been used by Australian conservationists to better examine and comprehend the environment and ecosystem inhabited by the fish. The cavefish resides in deep water columns that are rich in dissolved limestone. Due to relative densities and variable solubility, different depths in the water column are correlated to specific concentrations of dissolved materials. By examining the isotopic signatures of the cavefish’s skeletal apatite, conservationists were able to discover the exact depth the fish occupies.

As demonstrated by the cavefish, uptake of elements within vertebrates (O, C, Sr & others) generates a highly detailed record of the environmentally available isotopes at a given point in time; this availability can even be indicative of climate.As another illustration of application, Thure Cerling and others at the University of Utah have refined the technique of laser ablation to such quality and precision that they can use it to vaporize the apatite found in teeth. They then analyze the resulting gas via spectrometry to determine its isotopic components. The teeth can be examined to such resolution as to be able to report the dietary preferences of mammals between C3 and C4 plants. A similar isotopes-from-enamel strategy was employed by the folks from the University of Florida to expound several fallacies of niche conservatism…

Examinations of isotopic records are commonplace for many paleontologists. Uncountable volumes have been written on Foram O-18 isotopes and their relationship to periods of increased glaciation, and similar correlations of speleothems and C-13, but accurate isotopic records of both of these elements can be obtained from other sources as well - including mammals.

As a side note - skeletal tissues, which possess apatite, are very susceptible to diagenic processes that can cause recrystalization and alter results, but dental samples seem to be far more reliable when it comes to maintaining their original isotopic signatures. This coupled with the knowledge acquired in the past few decades in regarding incorporation of specific O-18 and C-13 isotopes into biological entities has brought to light a highly accurate record of climate change – and the critters that adapted to it.

Cretaceous Billabong Yields New Dinosaurs

Hocknull, S., White, M., Tischler, T., Cook, A., Calleja, N., Sloan, T., & Elliott, D. (2009). New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia PLoS ONE, 4 (7) DOI: 10.1371/journal.pone.0006190

Two newly identified sauropods and a new theropod have been excavated from the base of the Winton Formation near central Queensland. Fossilized pollens in-strata with the vertebrate remains indicate a Phimopollenites pannosus palynomorph Zone sequence and are thought to be Albian in age - about 100 million years old. In regards to ecology, cursory examinations of taphonomy and sedimentology show that the depositional conditions associated with the finds are akin to those found in modern oxbow lakes, or as the Aussies call them “billabongs”.

Although all three dinosaurs represent significant finds, the predatory theropod in particular is sure to bring publicity to the Australian Age of Dinosaurs Museum of Natural History and the Queensland Museum, which jointly worked on the excavations and diagnoses of the dinos. There’s nothing quite like a giant predatory allosauroid in terms of stirring the public’s interest in paleontology and stimulating museum attendance numbers.

According to Ben Kear of La Trobe University in Melbourne, "Australia is one of the great untapped resources in our current understanding of life from the Age of Dinosaurs. The discoveries...will definitely reinvigorate interest in the hitherto tantalizingly incomplete, but globally significant record from this continent..."


Meet “Matilda”

Named for the Diamantina River and one of Austrailia’a National songs (“Waltzing Matilda”), Diamantinasaurus matilda was a 16-meter long (52-foot) sauropod.


Nicknamed Matilda, she is the more stout of the two new sauropods and left behind a variety of fossils, including a pelvis:

Left reconstructed pelvis in lateral (A) view. Left ilium in anterior view (B) showing the position of the sacral vertebrae. Right pubis and ischium in medial (C), proximal (D) and lateral (E) views. Right ischium in lateral (F) and medial (G) views. Reconstructed right and left ischia in dorsal view. Abbreviations: ip, ischial peduncle; iip, iliac peduncle of ischium; of, obturator foramen; pa, pubio-ischial contact; pip, iliac peduncle of pubis; ppd, pubic peduncle; ppp, preacetabular process of ilium; s, sacrum; sym, fused ischial symphysis.

Meet “Clancy”

Wintonotitan wattsi, or “Watts' Winton Giant" was also around 16-meters in length, but sported a more elongate neck than Matilda.


Nicknamed Clancy, he was diagnosed from a variety of fossils, some partially articulated, including several vertebra:

Partial dorsal centrum in lateral (A) and posterior (B) views. Isolated neural spine in anterior view (C). Anterior caudal vertebrae of Wintonotitan wattsi. Anterior caudal vertebra in lateral (D) and anterior (E) views. Anterior caudal vertebra in posterior (F), lateral (G) and ventral (H) views. Anterior caudal vertebra in anterior (I), lateral (J) and ventral (K) views. Abbreviations: plc, pleurocoel; pcdl, posterior centrodiapophyseal lamina; prel, prespinal lamina; spl, spino-prezygopophyseal lamina.

Last, but not least - Meet “Banjo”

Called “Banjo” after Australian bush poet Banjo Patterson, Australovenator wintonensis was a 5-meter long (16-foot), 500 kilogram (1100 pounds) predator with three slashing claws.

"The cheetah of his time, Banjo was light and agile," "He's Australia's answer to Velociraptor, but many times bigger and more terrifying," said the article’s lead author Scott Hocknull of the Queensland Museum.

As evidence of his ferocity, here are a few of Banjo’s teeth:

Isolated teeth in labial (A, C, E, F, G, I, J, L) and labial (B, D, F, H, J, K) views. A–B. Anterior dentary tooth or premaxillary tooth. C–L. Dentary teeth.

Hocknull, S., White, M., Tischler, T., Cook, A., Calleja, N., Sloan, T., & Elliott, D. (2009). New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia PLoS ONE, 4 (7) DOI: 10.1371/journal.pone.0006190

All Images from Referenced Article

Associated Press News

Reuters News

Paleogenomics and the Temperate Goat

Ramírez, O., Gigli, E., Bover, P., Alcover, J., Bertranpetit, J., Castresana, J., & Lalueza-Fox, C. (2009). Paleogenomics in a Temperate Environment: Shotgun Sequencing from an Extinct Mediterranean Caprine PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005670

In order to evaluate new DNA sequencing technologies and better delineate the phylogeny of the caprinae (goat-antelope subfamily of Bovidae), several scientists from Spain recently extracted and sequenced 6,000 year old DNA from an extinct Balearic Island Cave Goat (Myotragus balearicus).

Myotragus balearicus Credit: Duke University

Myotragus balearicus is distinctive among the caprinae due to the presence of several features that are uncharacteristic for the group as a whole. Included with these unique anatomic morphologies are small stature (about 20-inches tall), forward looking eyes (stereoscopic vision) and dentition lacking upper incisors. Having evolved on the Spanish islands of Majorca and Minorca, the cave goat possesses an exceptional phylogenetic history and may hold important clues in its DNA as to how evolution functions in geographically isolated regions such as islands.

A challenge to past attempts at recovering and sequencing the genome of extinct animals is that DNA readily breaks down at elevated temperatures; so animals, such as the cave goat, which lived, perished and fossilized in warm temperate climates rarely maintained genetic remnants of sufficient quantity or quality to process in the lab.

Now that high-throughput DNA sequencing technologies are being developed and brought to bear, unique phylogenetic stories can be read from long extinct animals that were biogeographically located in warmer climes.

The Devonian Fishes that Got Away

In addition to remembrance ceremonies paying tribute to the men and women of the armed services, Memorial Day has become a day in which Americans head to the great out-of-doors to enjoy friends, family, picnics and nature. With this tradition in mind, I thought it fitting to briefly mention a couple of fish stories. These not so tall-tales are about a couple of good catches from the past year that somehow managed to get away from me.

The first story received quite a bit of publicity, it was in the news about a year ago and may be old news for some - but it's a fish worth a second look!

The fossil Materpiscis attenboroughi is a 380-million year old placoderm that was found with an intact umbilical cord! According to Dr. John Long of the Museum Victoria,“The discovery is certainly one of the most extraordinary fossil finds ever made. It is not only the first time ever that a fossil embryo has been found with an umbilical cord, but it is also the oldest known example of any creature giving birth to live young. The existence of the embryo and umbilical cord within the specimen provides scientists with the first ever example of internal fertilisation - i.e sex - confirming that some placoderms had remarkably advanced reproductive biology. This discovery changes our understanding of the evolution of vertebrates.”

Here's a Youtube Video (originally from Nature):




Long, J., Trinajstic, K., & Johanson, Z. (2009). Devonian arthrodire embryos and the origin of internal fertilization in vertebrates Nature, 457 (7233), 1124-1127 DOI: 10.1038/nature07732

Abstract: Evidence of reproductive biology is extremely rare in the fossil record. Recently the first known embryos were discovered within the Placodermi, an extinct class of armoured fish, indicating a viviparous mode of reproduction in a vertebrate group outside the crown-group Gnathostomata (Chondrichthyes and Osteichthyes). These embryos were found in ptyctodontids, a small group of placoderms phylogenetically basal to the largest group, the Arthrodira. Here we report the discovery of embryos in the Arthrodira inside specimens of Incisoscutum ritchiei from the Upper Devonian Gogo Formation of Western Australia (approximately 380 million years ago), providing the first evidence, to our knowledge, for reproduction using internal fertilization in this diverse group. We show that Incisoscutum and some phyllolepid arthrodires possessed pelvic girdles with long basipterygia that articulated distally with an additional cartilaginous element or series, as in chondrichthyans, indicating that the pelvic fin was used in copulation. As homology between similar pelvic girdle skeletal structures in ptyctodontids, arthrodires and chondrichthyans is difficult to reconcile in the light of current phylogenies of lower gnathostomes, we explain these similarities as being most likely due to convergence (homoplasy). These new finds confirm that reproduction by internal fertilization and viviparity was much more widespread in the earliest gnathostomes than had been previously appreciated.

Check out the Museum Victoria's Website for more info on Mother Materpiscis.

The second Devonian fish story that slipped away is one that has been retold since 1892 and really has some teeth to it!

In fact, teeth are all that it has to it – fossil teeth. Back in 1892 Woodward described the Devonian chondrichthyan Protodus jexi from the Lower Devonian Campbellton Formation in New Brunswick based on teeth recovered from the site. Several months ago, Susan Turner and Randall Miller published a follow-up examination of these teeth in Acta Geologica Polonica and determined the fish to be representative of the first predatory fish.

Here’s their conclusion:
Protodus jexi is known from one locality on the Campbellton shoreline of northern New Brunswick and represents the first chondrichthyan with predator style teeth. Given the nature of shark dentitions, the known 60 or so teeth might belong to one dentition. The paratypes and probably the syntypes include a tooth file of four associated dagger-like teeth with serrated cristae. The large subrectangular to D-shaped Protodus toothbase is similar and might be phylogenetically related to the cladodont type. Contemporaries Celtiberina and Stigmodus might be closely related or the similar tooth features might reflect functionality, with large laterally extended bases providing such ‘protodontidid’ teeth with a ‘solid’ root resisting movement and assisting an efficient predatory bite.

A Couple of Fossil Protodus jexi Teeth. Source Turner & Miller Article

SUSAN TURNER,RANDALL F. MILLER (2008). Protodus jexiWoodward, 1892 (Chondrichthyes),from the Lower Devonian Campbellton Formation, New Brunswick, Canada Acta Geologica Polonica, 58 (2), 133-145

The article is available HERE.

Mutualism in Situ – Fossilized Symbionts

A chunk of fossilized amber recovered from a mine in the Hukawng Valley of Myanmar has been found to encase a Cretaceous termite with several species of formerly egressing protozoa attached to an abdominal wound sustained more than 100 million years ago. This snapshot of symbiosis demonstrates that the relationship between the cellulolytic protist and its eusocial dwelling have been a long time in the making.

Cool fossil… Here’s the background section of the article:

Termites are one of the most successful eusocial insect groups today and certainly the most notorious as a result of their damage to human dwellings. Their success can be attributed in large part to microbial (especially protozoa and bacterial) symbionts harbored in their alimentary tract. Especially important are gut protists, which are essential for the survival of termites feeding on lignocelluloses. While termites do produce endogenous cellulases from salivary glands and gut cells, cellulolytic protists are crucial for the complete digestion of cellulose in wood-feeding termites. In the lower termites, these symbionts are mostly flagellates belonging to the Oxymonadida, Trichomonada and Hypermastigida. Flagellates associated with an Early Cretaceous lower termite of the family Kalotermitidae are described and compared with mutualistic flagellates of extant kalotermitids. This discovery shows that, while the protist species represent different genera and species, mutualistic associations between protists and termites had already been established some 100 million years ago. The present study represents the earliest fossil record of mutualism between microorganisms and animals.

The full text and several images can be found free HERE.

George O Poinar Jr. Description of an early Cretaceous termite (Isoptera: Kalotermitidae) and its associated intestinal protozoa, with comments on their co-evolution. Parasites & Vectors, 2009; 2 (12) DOI: 10.1186/1756-3305-2-12

Neil Shubin on Tiktaalik & Transitional Fossils

Neil Shubin, Associate Dean of the Biological Sciences Division at the University of Chicago describes how his diverse fossil findings allow him to devise hypotheses on how anatomical transformations occurred by way of genetic and morphogenetic processes.

New Study Merges Genetics, Demography and Paleoanthropology

Mitochondrial DNA from twelve Neanderthal fossil assemblages was sequenced, compared and correlated with morphological data from fossil skulls, limbs and dentary remains to render evidence for multiple demes of Neanderthals from across Asia and Europe.

According to the authors, this “…approach to Neanderthal variability, based on nucleotide sequences analysis, confirms from a genetic point of view the morphological variations between western and eastern Neanderthals and the existence of a southern group…”

The mtDNA portion of the study therefore supports prior determinations based on morphological analysis that at least three separate Neanderthal sub-groups (and possibly a fourth group from western Asia) emerged from an ancestral population approximately 130,000 years ago. Furthermore, there is evidence that these populations existed in a dynamic state of migration.

Figure 2. Neanderthal Group Distribution

Abstract:
The Neanderthals are a well-distinguished Middle Pleistocene population which inhabited a vast geographical area extending from Europe to western Asia and the Middle East. Since the 1950s paleoanthropological studies have suggested variability in this group. Different sub-groups have been identified in Western Europe, in southern Europe and in the Middle East. On the other hand, since 1997, research has been published in paleogenetics, carried out on 15 mtDNA sequences from 12 Neanderthals. In this paper we used a new methodology derived from different bioinformatic models based on data from genetics, demography and paleoanthropology. The adequacy of each model was measured by comparisons between simulated results (obtained by BayesianSSC software) and those estimated from nucleotide sequences (obtained by DNAsp4 software). The conclusions of this study are consistent with existing paleoanthropological research and show that Neanderthals can be divided into at least three groups: one in western Europe, a second in the Southern area and a third in western Asia. Moreover, it seems from our results that the size of the Neanderthal population was not constant and that some migration occurred among the demes.


In case you were wondering about genetic links to modern Homo sapiens, the study was limited to “…what occurred previous to the arrival of modern humans in the Neanderthal landscape and we therefore do not consider the potential phylogenetic relationship between Neanderthals and modern Humans.”

The article, in its entirety, is available at the below referenced link.

Fabre, V., Condemi, S., & Degioanni, A. (2009). Genetic Evidence of Geographical Groups among Neanderthals PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005151

“Extreme” Imperfection?

I just happened across a nifty little article from the Journal of Evolution: Education and Outreach. It discusses the fossil record, Darwin and other concepts such as “missing links” and transitional forms.

It’s jargon free and would be a good resource for teachers, or anyone interested in explaining to lay persons how fossils provide evidence for evolution.

It can be downloaded as a PDF - HERE.

Cretaceous Multituberculata from Australia

Thomas H. Rich (et. al.), Curator of Vertebrate Paleontology at the Museum of Victoria in Melbourne, Australia, recently published a description of dentary fragments from a member of the Multituberculata in the Journal Acta Palaeolontologica Polonica.

Several mammalian families have previously been identified from the Aptian formation (where the current fossil was found), most of these are believed to represent species endemic to Australia; however one family – the Ornithorhynchidae – have also been found in Argentina. Ornithorhynchidae, a group of monotremes, have been used to provide evidence for mammalian dispersal between South America and Australia during the Mesozoic.

According to the authors, these prehistoric platypuses provide biogeographical clues because “[g]iven the relative geographic positions of Australia and South America during the Mesozoic, it is reasonable to expect that were it then possible to do so, at least one of these terrestrial mammals would have traversed the Antarctic landmasses, in one direction or the other…”


Abstract:
A dentary fragment containing a tiny left plagiaulacoid fourth lower premolar from the Early Cretaceous (Aptian) of Victoria provides the first evidence of the Multituberculata from Australia. This unique specimen represents a new genus and species, Corriebaatar marywaltersae, and is placed in a new family, Corriebaataridae. The Australian fossil, together with meagre records of multituberculates from South America, Africa, and Madagascar, reinforces the view that Multituberculata had a cosmopolitan distribution during the Mesozoic, with dispersal into eastern Gondwana probably occurring prior to enforcement of climatic barriers (indicated by marked differentiation in regional floras) in the Early Cretaceous.

Holotype of multituberculate mammal Corriebaatar marywaltersae gen. et sp. nov. from Flat Rocks, Wonthaggi Formation (Aptian), Australia (NMV P216655), a left dentary fragment with p4 and anterior root of m1 in labial (A), lingual (B), and occlusal (C) views. Artwork by P. Trusler.

THOMAS H. RICH,et al. (2009). An Australian multituberculate and its palaeobiogeographic implications Acta Palaeolontologica Polonica

The article is available as a PDF HERE.

Beck, R., Godthelp, H., Weisbecker, V., Archer, M., & Hand, S. (2008). Australia's Oldest Marsupial Fossils and their Biogeographical Implications PLoS ONE, 3 (3) DOI: 10.1371/journal.pone.0001858

Omnivorous Pleistocene Bears Give Clues to Adaptation

By comparing the morphological features of Pleistocene bear fossils (Arctodus simus and Ursus spelaeus) with that of modern bears, scientists report that analogous cranio-mandibular structures indicate that even the prehistoric hyper carnivores had omnivorous tendencies.

These and other findings provide clues as to the niche plasticity and the ability of mammals to adapt to fluctuating climates.



'Knowing what the extinct bears ate is of utmost relevance to finding out about the evolution of carnivore niches in the Pleistocene when climatic conditions were changing', explains Borja Figueirido, lead author of the study and researcher for the Ecology and Geology Department of the Faculty of Sciences at the University of Málaga.



Figure Above: Landmarks used for describing cranial and mandibular shape. Cranium: (1) most postero-dorsal border of the canine alveolus, (2) most antero-dorsal border of the canine alveolus, (3) most antero-dorsal border of the I3, (4) most anterior edge of the nasal bones, (5) dorsal outline directly superior to post-orbital process, (6) dorsal outline directly superior to the end of the zygomatic arch, (7) most postero-ventral point of the occipital crest, (8) intersection between the occipital condyle and the occiput, (9) intersection between the occipital condyle and the paraoccipital process, (10) ventral tip of postglenoid process, (11) posterior edge of the upper tooth row, (12) point between the upper carnassial and the first upper molar, (13) anterior edge of the upper tooth row, (14) postero-dorsal border of the zygomatic arch, (15) dorsal tip of the frontal process of the zygomatic arch, (16) orbit midheigth, (17) ventral tip of the post-orbital process, (18) ventral intersection between the zygomatic arch and the axilla.Mandible: (1) antero-dorsal border of the incisive alveolus, (2) postero-dorsal border of the canine alveolus, (3) intersection between the trigonid/talonid notch of the lower carnassial and the dorsal border of the alveolus of this tooth, (4) posterior edge of the lower tooth row, (5) posterior edge of the coronoid process, (6) most posterior edge of the articular surface condyle, (7) tip of angular process, (8) ventral outline below the mesial end of the tooth row, (9) ventral outline below the trigonid/talonid notch of the lower carnassial, (10) most ventral point of the symphyseal region. Scale bar equals 5 cm. Deviations of the specimens analyzed from the consensus configuration of landmarks are shown.



Read the research article published in the Journal of Zoology - HERE.



Figueirido, B., Palmqvist, P., & Pérez-Claros, J. (2009). Ecomorphological correlates of craniodental variation in bears and paleobiological implications for extinct taxa: an approach based on geometric morphometrics Journal of Zoology, 277 (1), 70-80 DOI: 10.1111/j.1469-7998.2008.00511.x

Holotomography of a Carboniferous Chimaeroid

Impressive brain imagery of a 300 million year old fish…


“This application of holotomography confirms the rapidly growing possibilities of X-ray synchrotron phase imaging techniques in palaeontology, especially when dealing with the exceptional soft-tissue preservations. It imposes synchrotron radiation as a powerful tool for nondestructive imaging of fossils.”

From Abstract: “Living cartilaginous fishes, or chondrichthyans, include numerous elasmobranch (sharks and rays) species but only few chimaeroid (ratfish) species. The early history of chimaeroids, or holocephalans, and the modalities of their divergence from elasmobranches are much debated. During Carboniferous times, 358–300 million years (Myr) ago, they underwent a remarkable evolutionary radiation, with some odd and poorly understood forms, including the enigmatic iniopterygians that were known until now from poorly informative flattened impressions. Here, we report iniopterygian skulls found preserved in 3 dimensions in _300-Myr-old concretions from Oklahoma and Kansas…”

[Click Link Below to Continue]

Figure 1

Fig. 1. The anatomy of iniopterygians. (A) Reconstruction of Sibyrhynchus denisoni (based on ref. 5, not to scale). (B and C) Part (B) and counterpart (C) of a phosphatic nodule from the Pennsylvanian of Oklahoma (AMNH OKM38) containing the braincase and shoulder girdle of Sibyrhynchus sp. (D–F) Threedimensional reconstruction of the same specimen, obtained from conventional X-ray _CT images, showing the braincase in dorsal (D), ventral (E), and lateral (F) view, with associated teeth. (G–I) Three-dimensional reconstruction of the braincase, shoulder girdle, and pectoral fin elements of a sibyrhynchid iniopterygian from the Pennsylvanian of Kansas (KUNHM 21894), based on SR-_CT images. Braincase in dorsal (G), posterior (H), and ventral views, with articulated shoulder girdles and pectoral fin radials (I). Scale bar, 5 mm; f.IX and f.X, foramina for glossopharyngeus and vagus nerves).

Figure 2

Fig. 2. Braincase anatomy and exceptional brain preservation in a sibyrhynchid iniopterygian from the Pennsylvanian of Kansas. (A and B) articulated skull preserved in a nodule (KUNHM 22060) (see also Fig. S1) in dorsal (A) and anterior (B) view (arrow points forward). (C–Q), three-dimensional reconstructions and putative preserved brain structures of the same specimen, obtained from SR-_CT images (and holotomography for brain details). (C–H), Braincase, teeth, and lower jaw in lateral (C), anterior (D), ventral (E), posterior (F), and dorsal (G) view, showing by transparency the outline of the endocranial cavity and labyrinth (H). (I–K), Selected transverse (I and J), and horizontal (K) SR-_CT (holotomography) slices through the calcite-filled endocranial cavity, showing the probably phosphatized brain at the level of the rhombencephalon (I), hypophysis (J), and roof of the optic tectum and cerebellum (K). (L–N) Reconstruction of the endocranial cavity and otic capsule in dorsal (L andM) and lateral (N) view, showing the putative brain by transparency (Mand N). (O–Q), reconstruction of the putative phosphatized brain in dorsal (O), ventral (P), and lateral (Q) view. (Scale bar, 5mmfor A–N and 1mmfor I—K and O–Q. Asc, anterior semicircular canal; Cer, cerebellum; Ed, endolymphatic duct; Hsc, horizontal semicircular canal; Hyp, hypophysis; Olftr, canals for olfactory tracts; Opch, optic chiasm; Optec, optic tectum; Psc, posterior semicircular canal; II, optic nerve; III?, oculomotorius nerve?; IV?, trochlear nerve?; X?, roots of vagus nerve?).


Check out the article HERE.


Pradel, A., Langer, M., Maisey, J., Geffard-Kuriyama, D., Cloetens, P., Janvier, P., & Tafforeau, P. (2009). Skull and brain of a 300-million-year-old chimaeroid fish revealed by synchrotron holotomography Proceedings of the National Academy of Sciences, 106 (13), 5224-5228 DOI: 10.1073/pnas.0807047106

Caution: Wide Turns - Shell in Tow

If one were to draw a line depicting the rate of average global speciation or evolutionary novelty produced over the last billion years, this linear representation would certainly have a spike near the geologic time of the Cambrian Explosion. By about 500 million years ago, all present day phyla (i.e. body-plans, or animal “designs”) had representative species on the planet (with the exception of Bryozoa), including that of the most abundant animal and second-most abundant organism overall found on earth today (following only bacteria) - the arthropods. The challenges these arthropods overcame in their journey from the sea to a terrestrial existence were both immense and varied. In a recent article published in Geology, James W. Hagadorn and Adolf Seilacher find clues to one arthropod’s strategy to overcome the obstacles of dehydration and desiccation as it makes the transition landward. Within the Orthoquartzites of the Elk Mound Group in central Wisconsin, a type of ichnofossils called Protichnites tell a tale of behavioral adaptation and evolution.

Protichnites are trace fossils that display two parallel lines of tracks with a linear depression at the center. The parallel lines are essentially rows of footprints aligned towards the animal’s direction of travel. Carefully examined, these lines can be used to translate and interpret gait. In the case of the currently examined Elk Mound fossils, “the deeper impressions made by the rear pair of walking legs (i.e., the “pushers”) repeat symmetrically, in the same rhythm as the shell marks. This suggests synchronous movement of leg pairs, similar to modern Limulus and eurypterids, rather than the alternating gait reflected in tracks of crustaceans, scorpions, and insects.”

Photos from Referenced Article

The linear depression at the center of the Protichnites fossils is thought to be remnant drag marks from a tail. When turning, the arthropod’s tail swings outward from the direction of the turn, like a pendulum; these “wide turns” can provide biomechanical clues describing the gait of the animal.

One set of fossils studied by the authors, later named Protichnites eremite (eremite = Hermit), displayed a medial depression with irregular characteristics. “Instead of following the midline, its markings consist of oblique impressions that are always offset and shingled to the left side. It is unlikely that this represents an individual or population of individuals characterized by a malformed tail, because similar trackways of different widths occur on the same bedding plane and because such trackways occur on more than one horizon. Because there are no pushback hills on the rear sides of the oblique ‘tail’ impressions, it is also unlikely that this asymmetry reflects a behavioral strategy, in which the tail was bent sideways in order to assist in locomotion.”

If the irregular tail marks don’t represent a morphological malformation or provide evidence for locomotion, then what do they indicate, what’s the diagnosis? According to Hagadorn and Seilacher, “the impressions resemble the touch marks of a high-spired, dextrally coiled shell” similar to that carried by modern day hermit crabs.

The conclusion reached by the researchers is that the arthropods, while in transition to a terrestrial existence, probably “still left the water only for short durations, crawling around on the wet sand flats during low tides.” These intertidal sand flats proved ideal for promoting the growth of thin microbial films on which the light-footed arthropods left tracks and trails that later fossilized.

Using modern hermit crabs as an analog, the authors surmised that, “with their cuticular exoskeletons and stiff appendages, arthropods were particularly well preconditioned for terrestrialization. Nevertheless their early pioneers still required special adaptations, such as large body sizes and the use of foreign shells, to minimize water loss.” Transporting a shell on their back buffered the arthropods from arid conditions, but at the same time altered their gait to such an extent that we can read it in the fossils today.

Hagadorn, J., & Seilacher, A. (2009). Hermit arthropods 500 million years ago? Geology, 37 (4), 295-298 DOI: 10.1130/G25181A.1

Octopus Fossils from the Cretaceous

Cool fossil find!

New finds of 95 million year old fossils reveal much earlier origins of modern octopuses. These are among the rarest and unlikeliest of fossils. The chances of an octopus corpse surviving long enough to be fossilized are so small that prior to this discovery only a single fossil species was known, and from fewer specimens than octopuses have legs.

Everyone knows what an octopus is. Even if you have never encountered one in the flesh, the eight arms, suckers, and sack-like body are almost as familiar a body-plan as the four legs, tail and head of cats and dogs. Unlike our vertebrate cousins, however, octopuses don't have a well-developed skeleton, and while this famously allows them to squeeze into spaces that a more robust animal could not, it does create problems for scientists interested in evolutionary history. When did octopuses acquire their characteristic body-plan, for example? Nobody really knows, because fossil octopuses are rarer than, well, pretty much any very rare thing you care to mention.

The body of an octopus is composed almost entirely of muscle and skin, and when an octopus dies, it quickly decays and liquefies into a slimy blob. After just a few days there will be nothing left at all. And that assumes that the fresh carcass is not consumed almost immediately by hungry scavengers. The result is that preservation of an octopus as a fossil is about as unlikely as finding a fossil sneeze, and none of the 200-300 species of octopus known today has ever been found in fossilized form. Until now, that is.

Palaeontologists have just identified three new species of fossil octopus discovered in Cretaceous rocks in Lebanon. The five specimens, described in the latest issue of the journal Palaeontology, are 95 million years old but, astonishingly, preserve the octopuses' eight arms with traces of muscles and those characteristic rows of suckers. Even traces of the ink and internal gills are present in some specimens.

'These are sensational fossils, extraordinarily well preserved' says Dirk Fuchs of the Freie University Berlin, lead author of the report. But what surprised the scientists most was how similar the specimens are to modern octopus: 'these things are 95 million years old, yet one of the fossils is almost indistinguishable from living species." This provides important evolutionary information. "The more primitive relatives of octopuses had fleshy fins along their bodies. The new fossils are so well preserved that they show, like living octopus, that they didn't have these structures.' This pushes back the origins of modern octopus by tens of millions of years, and while this is scientifically significant, perhaps the most remarkable thing about these fossils is that they exist at all.

NEWS REPOST FROM HERE.

Reference:

Fuchs et al. New Octopods (Cephalopoda: Coleoidea) from the Late Cretaceous (Upper Cenomanian) of Hakel and Hadjoula, Lebanon. Palaeontology, 2009; 52 (1): 65 DOI: 10.1111/j.1475-4983.2008.00828.x

Vertebrate Proxies of Climate Change

Haphazardly racing around the net while pumped-up on Peet’s Sumatra coffee (so good!), I noticed that Jessica Blois and Elizabeth Hadley have an article being published in the Annual Review of Earth and Planetary Sciences this upcoming May. This is great news for me, because I have an interest in Cenozoic climate change and these folks are experts in the subject area; however, unfortunately for any readers of this blog lacking sufficient caffeine-ation, this post may seem a bit rambling… Consider it a refresher on vertebrate proxies of climate change.

"Organisms change through time. " - At first read this simple four-word sentence may seem rather barren of substance but within its basic grammar there exists a world of profound scientific insight and understanding. Evolution lies at the center of our biological universe, its principles are essential to science, and by grasping these principles we are able to efficiently navigate the worlds of ecology, paleontology and other life-linked sciences. Paleontologists and paleobiologists often utilize the ideas and tenants of organismal change as tools to decipher the remnants and records of past life in aspirations of better understanding not only biology and life, but also as a means of interpreting the physical history of our beloved planet Earth - the fundamental constants of chemistry and climate.

Numerous factors or mechanisms may signal biological change; natural selection, genetic drift and other gene flow can all introduce variation into a population, but these are merely the effects, or end products of change, what physically lies at the source of the process - what environmental factor triggered or was driving the selection, drift and flow?

What if, for example, some physical barrier was removed from a geographic region, thereby permitting the migration of a herd into previously unchartered lands, or the founding of a new population? Would the organisms – and their fossil remnants - be disrupted in such a way as to leave clues behind explaining the reason for increased rate of change or distribution? Less temporally dramatic, what if the seasonality of a region changed in such a way as to lengthen the mating season, or change the territoriality of a species? Would these events, be recorded in the fossil record? Undoubtedly yes!

Responsiveness of Vertebrates to Environment
Many studies of vertebrates have suggested that climate is the single best indicator of modern species richness. Over the past decade several different theories have been suggested in hopes of establishing a clear and precise relationship between organismal change and the environment. Some of these hypotheses are relatively familiar, such as Van Valen’s “Red Queen model,” and Vrba’s “Turnover-pulse model,” but others less so… Regardless, the majority of these models work to resolve one key question; how synchronous are climate and biotic change?

Vertebrates, and in particular mammals, are highly responsive to changes in the environment. Climate fluctuation can lead to an incredible amount of variation in the diet choice, distribution and even morphology of vertebrates. Even within Humans, biological anthropologists have identified trends associated with body size and appendage length based on climate; they refer to this correlation as Bermand and Allan’s Rule. It suggests that human populations occupying regions closer to the equator statistically contain individuals with larger body size and longer limbs relative to those who inhabit more pole-ward regions. This variation has arisen primarily to promote more efficient thermoregulation as to reduce body heat loss in cooler regions, and to promote cooling in warmer climates. Some vertebrates posses even finer genetic plasticity changing morphologically with what could be termed “hair triggers.”

One of the most highly variable vertebrates is the Pocket gopher (Thomomys spp). These gophers have been intensively studied as indicators of environmental change. Their populations, and individual morphology, have been shown to vary with in a period of less than ten years. The most easily recognized change in morphology is their body size - which fluctuates with everything from altitude to diet. Body size, in turn, has a noticeable effect on territory, fertility of females and distribution of the population (Hadly, 1996). These physiological changes, and the fossils they have left behind, have been intensely studied in relation to Late-Holocene Climatic changes.

Thomomys spp

One site in particular, Lamar Cave, located with in the boundaries of Yellowstone National Park, has been used by Elizabeth Hadley to make correlations to such historic climate changes as the Medieval Warm Period (MWP). Through comparison of fossil dental plates with those of modern descendants, Hadley has been able to demonstrate that during the MWP pocket gophers of this region had the smallest body size than at any other point in the paleontological record. Using similar comparisons she was also able to identify trends in morphology that correlated with the Little Ice Age (LIA) and other events including neoglaciation (Hadly, 1996). The response of vertebrates is not limited to the highly plastic morphology of pocket gophers. Many other vertebrates respond equally as readily to climate change. However, morphological change is not necessarily required of a species in order for it to serve as a climate proxy. During their lifespan, all organisms make detailed records of their environment. Through the fundamental life processes of cellular growth and repair vertebrates have the potential to generate detailed records of their environment. Just as the old cliché exemplifies, “you are what you eat.” This record can later be resurrected and deciphered from their fossil remains to help clarify the picture of the climate and chemistry they endured while alive.

Isotopes
Examinations of isotopic records are commonplace for many paleontologists. Uncountable volumes have been written on Foram 18-O isotopes and their relationship to periods of increased glaciation, or similar correlations of speleothems and 13-C, but accurate isotopic records of both of these elements can be obtained from other sources as well - including vertebrates.

Carbonate apatite is a primary constituent of both skeletal bones and dentition in the vertebrates. It is incorporated into the organism through diet and water uptake. The process is riddled with various “vital effects” but has nonetheless been found to be very accurate. In fact, many conservationist use this isotopic signature in vertebrates to better decipher the life histories of contemporary vertebrates in hopes of aiding in their preservation. For example, remains from the world’s largest cavefish (Milyeringa veritas) have been used by Australian conservationists to better examine and comprehend the environment and ecosystem which the fish inhabits. The cavefish lives in deep columns of water that are rich in dissolved limestone. The depths of the water column posses various corresponding incremental concentrations of dissolved materials and by examining the isotopic signatures of the fish’s skeletal apatite, conservationists were able to discover the exact depth the fish occupies.

Milyeringa veritas

Uptake of elements within vertebrates (O, C, Sr & others) generates a highly detailed record of environmentally available isotopes, and as one might guess, availability is indicative of climate.

As another example, Thure Cerling and others at the University of Utah have refined the technique of laser ablation to such quality and precision that they can use it to vaporize the apatite found in vertebrate teeth, and then analyze the gas to determine its isotopic components. They can examine the teeth to such resolution as to be able to report the dietary preferences of mammals between C3 and C4 plants. Previously, samples of fossil teeth or skeletal structures were far to rare to permit them to be thrown into a TIMS for examination, but now that laser ablation has reached such a high level of efficiency isotopic analysis can be made in the smallest and rarest of specimens with minimum impact on the fossil itself. Laser ablation can be used to examine the minute layer of enamel on the smallest of rodents and the most voluble of fossils on display at museums with little difficulty.

As a side note - many scientists have recently discovered that skeletal tissues, which possess apatite, are very susceptible to diagenic processes that can cause recrystalization and alter results, but dental samples seem to be far more reliable when it comes to maintaining their original isotopic signatures. This coupled with the knowledge acquired in the past few decades in regards to the incorporation of specific 18-O and 13-C isotopes into biological entities has brought to light a highly detailed and accurate record of climate change.

Similar techniques have been used to examine bone fragments from marine vertebrates. Some alteration of samples occurs during fossil formation in paleo-seawater environments which forces users of this technique to integrate other proxies of isotopic variation in their final estimates as a “check,” but as the technique begins to advance some of this error is likely to be eliminated. Others have also verified the validity of the use of dental enamel as an isotopic record. Schmitz and his colleagues examined fossil shark teeth from two different locations in Mississippi (one strata being mixed marine, the other brackish-water). Both samples demonstrated nearly identical isotopic signatures, even though they had been deposited in different strata, one with a high salinity concentration - previously shown to accelerate diagenesis. They also examined skeletal remains from marine vertebrates, but there seemed to be a significant error associated with those found in the marine strata.

Isotopic signatures can be very useful in the interpretation of paleoclimate, but in certain cases the mere presence of an organism at a given location - biogeography - can report volumes of information in regards to past climate.

Biogeography
The vertebrate fossil record can be extrapolated in terms of the diversity, divergence and variation of distinct animal groups over a geographic region to display, with accuracy, the impact of environmental change. Similarly, known vertebrate biogeographic patterns can be used to demonstrate specific climatic fluctuation both locally and on the global scale.

The Cenozoic has been marked by tremendous variation of climate. During the early portions of the Cenozoic high temperatures were the standard with the highest to be found in the Early to Middle Eocene, since then a falling temperature trend has been the rule. It was during the Eocene-Oligocene transition that Antarctica became isolated and sea levels dropped dramatically with the accumulation of ice caps, this had the effect of changing terrestrial habitats significantly. Throughout the Cenozoic, similar patterns of fluctuating glacioeustatic sea level events would continue to occur. Evidence of this can be found across the globe.

Thailand, in South-East Asia, is one of many regions that accurately record these glacioeustatic events through its vertebrate fossil record. Thailand is especially significant in that it separates two distinct biogeographical regions (Fig 1). The Indochinese region is located to the north of Thailand and the Sundaic region is located to the south. These two regions have significantly different climates and zoological compositions. Up until about 800kyr B.P. fluctuation of sea level was somewhat constant in the region of Thailand, with the average being somewhere around 70m below the modern, and the greatest change being no more than 100m below the modern. However, near the 800kyr B.P. mark level dropped more dramatically, some fluctuations going as low as 170m below modern sea levels. This had the effect of constructing a land bridge between the Indochinese and Sundaic biogeographical regions, thus permitting the migration of a large variety of animals, including mammals. Through careful comparison of the fossils these migrating animals left behind, and the extant species found in both the Indochinese and Sundaic regions, certain conclusions can be established in regards to their phylogenies. The presence of fossil mammals with Indochinese affinity in the Sundaic regions, and the presence of Sundaic mammals in Indochina suggest some mode of migration in the past that is prevented in modern times by the sea acting as a barrier. Through radio dating of remains, an estimated time for the existence of the land bridge can be calculated, thus the fossil mammals provide dates for periods of reduced sea levels, and in turn, periods of increased glaciation.

FIGURE 1--- Land bridge linking distinct biogeographical regions in Thailand

Thailand is not unique in its ability to provide vertebrate proxies of climate change. Similar scenarios have been played out across the globe. Grenada offers another example of vertebrate biogeography acting as an indicator of sea level change due to increased glaciation.

Grenada has a rather sparse population of indigenous mammals at present, and bats represent the majority of these species. However, paleontologists have recently uncovered a variety of fossil mammals near the Grenadine coast dating from the Pliocene. These species, such as representative capybaras and sloth, did not arise independently on Grenada and then become extinct. Their lineages suggest that they arrived on Grenada from the South American mainland, where their descendants can still be found today. Grenada is located on the Southern Antilles Arc Platform, an elongate sub ocean structure that extends some 180km. This arc provides a base for several small islands and at its closest point comes to with in 40km of South America. During the Pliocene, a combination of low sea levels and tectonic activity provided a land bridge that may have conjoined Grenada with South America thus allowing for the migration of mammals. Through accurate dating of these fossil remains and of the associated tectonic activity estimates for late Pliocene glaciations can be made.


Through biogeographic research, other evidence can be in found with the target of determining periods of climatic change that are independent of sea level, and glacioeustaic events. Many other factors can have the effect of generating temporary corridors that permit faunal exchange. A “corridor” is simply a narrow tract, or pathway, which allows for the exchange of animals from one side to another. These corridors can be created by various means, including the growth of a forest.


The western Canadian ice-free corridor is a continuous tract of land that extends from Alberta, Northward to the Arctic Ocean (fig 2). This corridor separates Eastern and Central Canada from the Western Coastal portions of the Country. At one point in the past this corridor was closed to faunal exchange do to the advancing Laurentide ice sheet; however, near the close of the Pleistocene the ice retreated significantly enough to open the corridor temporarily, before finally closing again. This second closing of the corridor was not due to advancing ice caps, but rather to the growth of Boreal forests.

FIGURE 2---- Ice-free corridor, shaded region

These forests impeded the exchange of fauna between the Bering Strait (and in turn Asia) located in the North West, and Eastern Canada. This meant that any faunal exchange would need to occur between the Plains of the United States and the Bering Strait, which, as coincidence would have it, was a corridor itself. Evidence for this “faunal funneling” can be found through out the plains. The presence of fossil mammals such as wooly mammoths, camels, horses, buffalo, lemmings and even lions give support for the corridor closing during this period. These animals marked their migratory trails with their very own remains, which are now found as fossils - littering their previous routes. Through accurate dating it can be determined exactly when this western Canadian corridor was closed by the growth of forests, and reductively, when climate would support such lush growth.

Interpretation of paleoclimate is a highly important field of study. Not only is it required to better understand the physical and biological history of our planet, but also to endow us with the knowledge needed to prepare for tomorrows’ inevitable changes. The Cenozoic has been marked by extreme change of temperature and climate as a whole, many such changes visible on a short-term scale. This period in geological history has seen everything from periods of hot and dry, to glaciation. To better understand the past and future effects on humans we must discover how it impacted the existence of other animals, in particular, other mammals. To better understand their evolutionary responses to climate, careful analysis of their fossil record must be made. Their physiology, morphology, biochemistry and even behavioral responses record every detail of their natural histories and the climates that they endured. Organisms change through time; the trick to rendering these records lays in the accurate translation of their fossil remains. To accomplish this end, the vertebrate indicators of climate change are an essential and indispensable tool and I very much look forward to reading more about them in May.

RECCOMENDED READING

Alberdi, M. et al. 2001. Vertebrate taphonomy in circum-lake environments: Three cases in the Guadix-Baza Basin (Granada, Spain). Paleogeogrphy, Paleoclimatology, Paleoecology. 165:1-26.

Badgley, C; Behrensmeyer, A. 1995. Preservational, Paleoecological and evolutionary patterns in the Paleogene of Wyoming-Montana and the Neogene of Pakistan. Paleogeography, Paleoclimatology, Paleoecology. 115: 319-340.

Badgley, C; Behrensmeyer, A. 1995. Two long geological records of continental ecosystems. Paleogeography, Paleoclimatology, Paleoecology. 115:1-11.

Barnosky, A. 2001. Distinguishing the effects of the Red Queen and the Court Jester on Pliocene Mammal Evolution in the Northern Rocky Mountains. Journal of Vertebrate Paleontolgy. 21:172-185.

Barrat, J; etal. 2000. Strontium isotopes in biogenic phosphates from a Neogene marine formation: implications for paleoseawater studies. Chemical Geology. 168:325-332.

Bromage, T.; etal. 1995. Paleobiography of the Molawi Rift: Age and vertebrate paleontology of the Chiwando beds, northern Molawi. Journal of Human Evolution. 28:37-57.

Bussuyt, F; Milankovitch, M. 2001. Amphibians as Indicators of Early Territory “ Out- of -India” Dispersal of Vertebrates. Science. 292:93-100.

Cerling, T; Sharp,Z. 1996. Stable carbon and oxygen isotope analysis of fossil tooth enamel using laser ablution. Paleogeography, Paleoclimatology, Paleoecology. 126:173-186.

Coope, G.R. et al. 1997. Climatic and Environmental Reconstructions based on fossil assemblages from Middle Devension (Weichselion) deposits of the river Thames at South Kensington, Central London, UK. Quaternary Science Reviews. 16:1163-1195.

Cruzan, M and Templeton, A. 2000. Paleoecology and Coalescence: phylographic analysis of hypothesis from the fossil record. TREE. 15:491-496.

Dennistan, R. etal. 1999. Integrating stalagmite, vertebrate and pollen sequences to investigate Holocene vegetation and climate change in the southern Midwestern United States. Quaternery Research. 52:381-387.

Flynn, J; Wyss, A. 1998. Recent advances in South American mammalian paleontology. TREE. 11:449-454.

Gao, C. et al. 2000. Last interglacial and Devension deposits of the river Great Ouse at Toolpack Form, Fenstanton, Cambrideshire, UK. Quarternary Science Reviews. 19:787-810.

Kerr, J; Packer, L. 1999. The environmental basis of North American species richness patterns among Epicauta (caleoptera: Meloidae). Biodiversity and Conservation. 8:617-628.

MacDonald, G; McLeod, T. 1996. The Holocene closing of the ‘ice-free’ corrider: A Biographical Perspective. Quarternary International. 32:57-95.

MacPhee, R.; Singer, R.; Diamond, M. 2000. Late Cenozoic land mammals from Grenada, lesser Antilles Island-Arc. American Museum Novitates. 3302:1-20.

Scasso, R.; Castro, L. 1999. Cenozoic phosphatic deposits in North Patagonia, Argentina: Phosphogenesis, sequence-stratigraphy and paleooceanography. Journal of South American Earth Sciences. 12:471-487.

Schmitz, B. et al. 1997. Testing 87Sr/86Sr as a paleosalinity indicator on mixed marine, brackish-water and terrestrial vertebrate skeletal apatite in late Paleocene-early Eocene near coastal sediments, Mississippi. Chemical Geology. 140:275-287.

Vigne, Jean-Denis. 1996. Small mammal fossil assemblages as indicators of environmental change in northern Corsica during the last 2500 years. Journal of Archeological Science. 23:199-215.

Wing, S; Alroy, J; Hickey, L. 1995. Plant and mammal diversity in the Paleocene to early Eocene of the Bighorn Basin. Paleogeography, Paleoclimatology, Paleoecology. 115:117-155.


Elizabeth A. Hadly (1997). Evolutionary and ecological response of pocket gophers (Thomomys talpoides) to late-Holocene climatic change Biological Journal of the Linnean Society, 60 (2), 277-296 DOI: 10.1111/j.1095-8312.1997.tb01496.x

William F. Humphreys (2001). Milyeringa veritus (Eleotridae), a remarkably versatile cave fish
from the arid tropics of Northwestern Australia.
Environmental Biology of Fishes, 62 (1/3), 297-313 DOI: 10.1023/A:1011880726946

Fossils Discovered

Currently out of office - just a quick news story of interest...

Scientists are studying a huge cache of Ice Age fossil deposits recovered near the famous La Brea Tar Pits in the heart of the nation's second-largest city.

Among the finds is a near-intact mammoth skeleton, a skull of an American lion and bones of saber-toothed cats, dire wolves, bison, horses, ground sloths and other mammals.
Researchers discovered 16 fossil deposits under an old parking lot next to the tar pits in 2006 and began sifting through them last summer. The mammoth remains, including 10-foot-long tusks, were in an ancient riverbed near the fossil cache.

Officials of the Page Museum at the tar pits plan to formally announce their findings on Wednesday. The discoveries could double the museum's Ice Age collection.
Such a rich find usually takes years to excavate. But with a deadline looming to build an underground parking garage for the next-door art museum, researchers boxed up the deposits and lifted them out of the ground using a massive crane.

"It's like a paleontological Christmas," research team member Andie Thomer wrote in a blog post in July.

The research dubbed "Project 23" — because it took 23 boxes to house the deposits — uncovered fossilized mammals as well as smaller critters including turtles, snails and insects. Separately, scientists found a well-preserved Columbian mammoth that they nicknamed Zed.
An examination reveals Zed, which is 80 percent complete, had arthritic joints and several broken and re-healed ribs — an indication that he suffered a major injury during his life.

"It's looking more and more as if Zed lived a pretty rough life," Thomer blogged in December.
Some scientists not connected with the discovery said this is the first significant fossil find since the original excavations at the tar pits more than a century ago.

"Usually these things are either lost in the mixing or not recovered in the processing of the oily sand and soil they occur in," paleontologist Jere H. Lipps of the University of California, Berkeley wrote in an e-mail to The Associated Press.

The La Brea Tar Pits ranks among the world's famous fossil sites. Between 10,000 and 40,000 years ago, mammoths, mastodons, saber-tooth cats and other Ice Age beasts became trapped by sticky asphalt that oozing upward through cracks and fissures in the ground. The newly recovered fossils were also in asphalt.

Since 1906, more than a million bones have been unearthed from the sticky ponds.

Source: Here

Chinese cheetahs and the foundations of Felidae

The cheetah, probably best known from zoology classes as the archetypical bottleneck species, has made headlines as of recent for a suggested Chinese ancestry. More specifically, recently published research by Per Christiansen and Ji H. Mazák seems to indicate a cheetah lineage from the Late Pliocene of Asia as opposed to one stemming from North America (the N.A. origin currently holding the majority opinion).

Although a tremendous find, the fossil skull serving as the basis for this “out of Asia hypothesis” may already be coming under fire. Professor Deng Tao of the Chinese Academy of Sciences is of the opinion that the skull may not be a member of the modern cheetah genus (Acinonyx), but rather the more primitive genus Sivapanther, described previously by his team.

A felid aficionado I am not; however it seems that any isolated find, such as that described by Christiansen and Mazák, may not possess sufficient substance as to assert a clean delineation of any lineage or origin locale. In the case of the cheetah, or any other felid for that matter, such conclusions could be viewed as even more tenuous due to considerable disagreement and recent taxonomic revision in regards to the cat family in general.

Though admittedly fervent about field work and getting my hands dirty, it’s important to take all descriptive and taxonomic labors in context with other taxa related research. In this instance, a review of work performed mapping felid nuclear mitochondrial DNA (numt) would be essential, as would a quick comparison to fossil evidence used in development of standard reference materials, such as that used in conjunction with more collaborative publications (example Mammal Species of the World).

Taken as a whole, the skull is a great find; however I’m inclined to think that the cheetah's story is far from being complete…

P. Christiansen, J. H. Mazak (2009). A primitive Late Pliocene cheetah, and evolution of the cheetah lineage Proceedings of the National Academy of Sciences, 106 (2), 512-515 DOI: 10.1073/pnas.0810435106