Category Archives: News

Camels in Beringia!

Last interglacial western camel (Camelops hesternus) from eastern Beringia
Grant D. Zazula, Derek G. Turner, Brent C. Ward, Jeffrey Bond

Quaternary Science Reviews
Volume 30, Issues 19-20, September 2011, Pages 2355-2360
doi:10.1016/j.quascirev.2011.06.010

Abstract

Western camel (C. hesternus) fossils are rare from Eastern Beringia, thus there is little available information on their chronology, paleoecology, and biogeography in this region. In August of 2010, a partial proximal phalanx of a western camel was recovered from a sedimentary exposure along the White River, in the formerly glaciated terrain of southwest Yukon, northwest Canada. The fossil specimen was recovered in situ from sediments that are correlated by stratigraphic, tephra and radiocarbon data to the Marine Isotope Stage (MIS) 5 interglacial period (Sangamonian). Associated paleoenvironmental data indicates that this western camel inhabited a shrub tundra ecosystem that did not include spruce trees or boreal forest during a relatively cold interval between MIS 5e and 5a. This is the oldest reliably dated western camel fossil from Eastern Beringia and supports the model of range expansion for this species to the high latitudes of northwest North America during the last interglacial (sensu lato).

Columbian mammoth interbreeding with woolly mammoth

Complete Columbian mammoth mitogenome suggests interbreeding with woolly mammoths

Jacob Enk*, Alison Devault, Regis Debruyne, Christine E King, Todd Treangen, Dennis O’Rourke, Steven L Salzberg,Daniel Fisher, Ross MacPhee and Hendrik Poinar*

Late Pleistocene North America hosted at least two divergent and ecologically distinct species of mammoth: the periglacial woolly mammoth (Mammuthus primigenius) and the subglacial Columbian mammoth (Mammuthus columbi). To date, mammoth genetic research has been entirely restricted to woolly mammoths, rendering their genetic evolution difficult to contextualize within broader Pleistocene paleoecology and biogeography. Here, we take an interspecific approach to clarifying mammoth phylogeny by targeting Columbian mammoth remains for mitogenomic sequencing. We sequenced the first complete mitochondrial genome of a classic Columbian mammoth, as well as the first complete mitochondrial genome of a North American woolly mammoth. Somewhat contrary to conventional paleontological models, which posit that the two species were highly divergent, the M. columbi mitogenome we obtained falls securely within a subclade of endemic North American M. primigenius. Though limited, our data suggest that the two species interbred at some point in their evolutionary histories. One potential explanation is that woolly mammoth haplotypes entered Columbian mammoth populations via introgression at subglacial ecotones, a scenario with compelling parallels in extant elephants and consistent with certain regional paleontological observations. This highlights the need for multi-genomic data to sufficiently characterize mammoth evolutionary history. Our results demonstrate that the use of next-generation sequencing technologies holds promise in obtaining such data, even from non-cave, non-permafrost Pleistocene depositional contexts.

Genome Biology 2011, 12:R51 doi:10.1186/gb-2011-12-5-r51
http://genomebiology.com/2011/12/5/R51/abstract

____________________________________
Laura

Fossil Evidence on Origin of the Mammalian Brain

Timothy B. Rowe, Thomas E. Macrini, Zhe-Xi Luo

ABSTRACT

Many hypotheses have been postulated regarding the early evolution of the mammalian brain. Here, x-ray tomography of the Early Jurassic mammaliaforms Morganucodon and Hadrocodium sheds light on this history. We found that relative brain size expanded to mammalian levels, with enlarged olfactory bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two evolutionary pulses. The initial pulse was probably driven by increased resolution in olfaction and improvements in tactile sensitivity (from body hair) and neuromuscular coordination. A second pulse of olfactory enhancement then enlarged the brain to mammalian levels. The origin of crown Mammalia saw a third pulse of olfactory enhancement, with ossified ethmoid turbinals supporting an expansive olfactory epithelium in the nasal cavity, allowing full expression of a huge odorant receptor genome.

Science 20 May 2011: Vol. 332 no. 6032 pp. 955-957 DOI: 10.1126/science.1203117

http://www.sciencemag.org/content/332/6032/955.full

http://beta.news.yahoo.com/ancient-furry-mammals-had-big-brains-smell-191357916.html
__________________________________
Laura

New Captorhinid Reptile Found in China

A new captorhinid reptile, Gansurhinus qingtoushanensis, gen. et sp. nov., was found from Xidagou Formation (Middle Permian) at Qingtoushan (Dashankou) locality near Yumen, Gansu Province, and from Naobaogou Formation (Late Permian) in Baotou, Nei Mongol, China, as reported in the recent issue of Naturwissenschaften 98 (435–441), 2011. The find provides new evidence for further studies on the evoluting and paleogeography of captorhinid reptiles.

http://english.ivpp.cas.cn/rh/rp/201105/t20110523_70125.html

—
Majid

Brain evolution and other Mesozoic mammal stuff

Some new meso-mammal-papers picked up from Dinosaur Discussion List… 🙂

–Mikko H.

Some recent items about Mesozoic mammals.

In the new issue of Science:

R. Glenn Northcutt (2011)
Perspective Paleontology: Evolving Large and Complex Brains.
Science 332 (6032): 926-927 (20 May 2011):
DOI: 10.1126/science.1206915
http://www.sciencemag.org/content/332/6032/926.summary

Summary
During the Mesozoic (∼250 million to 65 million years ago), two
distantly related groups of reptiles-the cynodont (or mammal-like) reptiles
and the coelurosaurian theropod dinosaurs-gave rise to mammals and birds,
respectively. Both mammals and birds evolved brains some 10 times as large,
relative to a given body weight, as those of their ancestors (1). In both
groups, these brains contributed to the evolution of the ability to control
body temperature (endothermy) and complex social interactions, including
parental care and a reliance on learning that even involves tool use (2,
3). The size of most parts of the brain increased in birds and mammals, but
the cerebral hemispheres and cerebellum, both of which are involved in
sensory and motor integration, underwent particularly spectacular
development (see the figure). Although mammals and birds evolved from
distantly related groups of reptiles, the higher integrative centers and
circuitry of their cerebral hemispheres are very similar, and comparative
neurobiologists continue to vigorously debate whether these centers evolved
from the same ancestral neural centers (4, 5) or from different ones (6-8).
Speculation about the evolutionary steps leading to large and complex
mammalian and avian brains is equally contentious and unresolved, in part
because of the rarity of fossil skulls and, until recently, the need to
destroy such skulls in order to expose the endocasts (casts molded by the
cranial cavity). Typically, endocasts are the only record of the brain’s
outward appearance in a transitional form, because brains themselves are
rarely fossilized.

Timothy B. Rowe, Thomas E. Macrini, and Zhe-Xi Luo (2011)
Fossil Evidence on Origin of the Mammalian Brain.
Science 332(6032): 955-957 (20 May 2011):
DOI: 10.1126/science.1203117
http://www.sciencemag.org/content/332/6032/955.abstract

Abstract
Many hypotheses have been postulated regarding the early evolution of the
mammalian brain. Here, x-ray tomography of the Early Jurassic mammaliaforms
Morganucodon and Hadrocodium sheds light on this history. We found that
relative brain size expanded to mammalian levels, with enlarged olfactory
bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two
evolutionary pulses. The initial pulse was probably driven by increased
resolution in olfaction and improvements in tactile sensitivity (from body
hair) and neuromuscular coordination. A second pulse of olfactory
enhancement then enlarged the brain to mammalian levels. The origin of
crown Mammalia saw a third pulse of olfactory enhancement, with ossified
ethmoid turbinals supporting an expansive olfactory epithelium in the nasal
cavity, allowing full expression of a huge odorant receptor genome.

J. David Archibald, Yue Zhang, Tony Harper and Richard L. Cifelli (2011)
Protungulatum, Confirmed Cretaceous Occurrence of an Otherwise Paleocene
Eutherian (Placental?) Mammal.
Journal of Mammalian Evolution (advance online publication)
DOI: 10.1007/s10914-011-9162-1
http://www.springerlink.com/content/n661405803q511n8/

Neither pre-Cenozoic crown eutherian mammals (placentals) nor archaic
ungulates (“condylarths”) are known with certainty based on the fossil
record. Herein we report a new species of the Paleocene archaic ungulate
(“condylarth”) Protungulatum from undisputed Late Cretaceous aged rocks in
Montana USA based on an isolated last upper premolar, indicating rare
representatives of these common early Tertiary mammals appeared in North
America a minimum of 300 k  years before the extinction of non-avian
dinosaurs. The other 1200 mammal specimens from the locality are
characteristic Late Cretaceous taxa. This discovery overturns the current
hypothesis that archaic ungulates did not appear in North America until
after the Cretaceous/Tertiary (K/T) boundary and also suggests that other
reports of North American Late Cretaceous archaic ungulates may be correct.
Recent studies, including ours, cannot determine whether Protungulatum does
or does not belong to the crown clade Placentalia.

A few months old but its free–pdf of short survey article about Chinese
Mesozoic mammals:
http://english.ivpp.cas.cn/rh/as/201012/P020101207396650166902.pdf

A. O. Averianov and A. V. Lopatin (2011)
Phylogeny of triconodonts and symmetrodonts and the origin of extant
mammals.
Doklady Biological Sciences 436(1): 32-35,
DOI: 10.1134/S0012496611010042
http://www.springerlink.com/content/3x027744038g6866/
(no abstract)

Canine Tooth from Peking Man Identified in Sweden!

Paleontologists from Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, and Swedish colleagues from Uppsala University, recently identified a unique canine tooth from Peking Man among the contents of the 40 cartons left unopened and forgotten at the Museum of Evolution at Swedish Uppsala University.

“The tooth has not been touched since it was dug up in the 1920s in China. We and our Chinese colleagues are overwhelmed. With today’s technology, a canine tooth that has not been handled can tell us so much more than in the past, such as what they ate,” said Per Ahlberg, professor of evolutionary developmental biology at Uppsala University.

Fossils from well-known Peking man are extremely rare, as most of the finds disappeared during World War II. All that remains in China today are five teeth and a few pieces of skull bone that were found in the 1950s and 1960s.

Swedish paleontologists were the first group of scientists to go to China in the early 20th century to carry out a series of expeditions in collaboration with Chinese colleagues. They found large numbers of fossils of dinosaurs and other vertebrates. The material was sent to Sweden and the well-known paleontologist Carl Wiman identified and described the fossils. But when the policy of research changed after Wiman’s death, 40 cartons were left unopened and forgotten. Just a few weeks ago, Ahlberg and his colleague Martin Kundrat, and Museum Director Jan Ove Ebbestad noticed the cartons in a museum storeroom. They have gone through the material and contacted Drs. LIU Wu and TONG Haowen, from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, who were excited and flew to Sweden to confirm the identification of the tooth.

“This is an extremely important find. It is the only canine tooth in existence. It can yield important information about how Homo erectus lived in China,” said LIU Wu.

The Museum of Evolution kept the best collection of Chinese fossils of dinosaurs and other vertebrates outside of China, and the contents of the 40 cartons further enhance the value of the collection. The fossil material comes from several different areas in China. For example, specimens from Zhoukoudian, southwest of Beijing, were made of skulls and other skeletal parts, including this canine tooth from Homo erectus or Peking man.

—
Majid

Eat Nuts.. or.. Grass? Huh?

Thure E. Cerling, Emma Mbua, Francis M. Kirera, Fredrick Kyalo Manthi, Frederick E. Grine, Meave G. Leakey, Matt Sponheimer, and Kevin T. Uno

Diet of Paranthropus boisei in the early Pleistocene of East Africa
PNAS 2011 ; published ahead of print May 2, 2011, doi:10.1073/pnas.1104627108

Abstract

The East African hominin Paranthropus boisei was characterized by
a suite of craniodental features that have been widely interpreted
as adaptations to a diet that consisted of hard objects that required
powerful peak masticatory loads. These morphological adaptations
represent the culmination of an evolutionary trend that
began in earlier taxa such as Australopithecus afarensis, and presumably
facilitated utilization of open habitats in the Plio-Pleistocene.
Here, we use stable isotopes to show that P. boisei had a diet
that was dominated by C4 biomass such as grasses or sedges. Its
diet included more C4 biomass than any other hominin studied
to date, including its congener Paranthropus robustus from South
Africa. These results, coupled with recent evidence from dental
microwear, may indicate that the remarkable craniodental morphology
of this taxon represents an adaptation for processing
large quantities of low-quality vegetation rather than hard objects.

Toothache in Permian reptile

In popular news:

http://news.discovery.com/animals/ancient-reptile-toothache-110418.html

The actual paper:

Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance

Robert R. Reisz & Diane M. Scott & Bruce R. Pynn & Sean P. Modesto, Naturwissenschaften DOI 10.1007/s00114-011-0792-1

We report on dental and mandibular pathology in Labidosaurus hamatus, a 275 million-year-old terrestrial reptile from North America and associate it with bacterial infection in an organism that is characterized by reduced tooth replacement. Analysis of the surface and internal mandibular structure using mechanical and CT-scanning techniques permits the reconstruction of events that led to the pathology and the possible death of the individual. The infection probably occurred as a result of prolonged exposure of the dental pulp cavity to oral bacteria, and this exposure was caused by injury to the tooth in an animal that is characterized by reduced tooth replacement cycles. In these early reptiles, the reduction in tooth replacement is an evolutionary innovation associated with strong implantation and increased oral processing. The dental abscess observed in L. hamatus, the oldest known infection in a terrestrial vertebrate, provides clear evidence of the ancient associa- tion between terrestrial vertebrates and their oral bacteria.

-Laura

Definitive* proof of multiple origins of Definitive Mammalian Middle Ear (DMME)

A very nice paper and ‘News and Views’ on the discovery of yet another incredibly well preserved early mammal from Liaoning, China. This one preserved both ossified Meckels cartilage (OMC, already known from close relatives) AND attached to this are ALL of the middle ear bones! These are adrift of the dentary where they are thought to have moved from into the ear of mammals, yet they are still attached to it via this OMC. As the new beastie is found ‘higher’ up the phylogenetic tree than monotremes and multituberculates, both known to have the DMME, and plenty of close and distant relatives have either the OMC or a groove where it is thought the OMC lies, it indicates that the DMME, once thought to indicate the origin of mammalia, has likely evolved multiple times independently:

http://www.nature.com/nature/journal/v472/n7342/full/nature09921.html

and News and Views on the paper:

http://www.nature.com/nature/journal/v472/n7342/full/472174a.html

* This is ‘definitive’ if you accept a) the phylogeny presented and b) that this is not simply a reversal (though the presence of the ossified meckels cartilage in multiple taxa indicates this is unlikely). The phylogeny is open to discussion however, as it is partly based on the hypothesis that tribosphenic teeth also evolved independently at least twice, and there is evidence both for and against this. If you accept both of these, it’s homoplasy a go go in the two key mammalian morphological key innovations!

-Ian