Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia
Jason J. Head, Gregg F. Gunnell, Patricia A. Holroyd, J. Howard Hutchison and Russell L. Ciochon
http://rspb.royalsocietypublishing.org/content/280/1763/20130665
and some press
http://www.nature.com/nature/journal/v498/n7453/full/498141d.html?WT.ec_id=NATURE-20130613
http://edition.cnn.com/2013/06/05/us/climate-change-jim-morrison-lizard/index.html
– Jacqueline
Far from teeth but interesting finding for evolutionary purposes
http://www.pnas.org/content/110/17/E1594.full.pdf+html
– Elodie
Hi,
That paper might interest some of you
Mechanical basis of morphogenesis and convergent
evolution of spiny seashells
Régis Chirat, Derek E. Moultonb, and Alain Goriely
Abstract
Convergent evolution is a phenomenon whereby similar traits
evolved independently in not closely related species, and is often
interpreted in functional terms. Spines in mollusk seashells are
classically interpreted as having repeatedly evolved as a defense in
response to shell-crushing predators. Here we consider the morphogenetic
process that shapes these structures and underlies their
repeated emergence. We develop a mathematical model for spine
morphogenesis based on the mechanical interaction between the
secreting mantle edge and the calcified shell edge to which the
mantle adheres during shell growth. It is demonstrated that a large
diversity of spine structures can be accounted for through small
variations in control parameters of this natural mechanical process.
This physical mechanism suggests that convergent evolution of
spines can be understood through a generic morphogenetic process,
and provides unique perspectives in understanding the phenotypic
evolution of this second largest phylum in the animal kingdom.
Best,
Elodie
VIIKKI BIOCENTER LECTURE
NOTE TIME: on Tuesday, March 26 at 10.15
Auditorium 1041, Biocenter 2
http://www.biocenter.helsinki.fi/viikki_lectures.html
Manfred Laubichler (Arizona State University, USA): The past, present and future of developmental evolution: A drama in three acts
Host: Jukka Jernvall
Manfred Laubichler’s research covers three areas. His work in theoretical biology is focused on conceptual and mathematical issues, such as the problem of defining biological characters in development and evolution, the homology problem, and the theory of epistatic and epigenetic effects. In evolutionary developmental biology Laubichler focuses on social insects as a model system. Finally, he is interested in the history of theoretical biology, embryology and developmental biology. In his presentation, Laubichler will discuss broadly issues related to molecular and computational challenges in developmental evolution studies.
Dr. Laubichler is Professor of Theoretical Biology and History of Biology; Director, Center for Social Dynamics and Complexity; Associate Director, Origins Project; Adjunct Scientist, Marine Biological Laboratory, Woods Hole; External Professor, Santa Fe Institute.
Selected references:
http://www.youtube.com/watch?v=tR2dLrvFx7c
Hartfelder et al., (2012) Development and evolution of caste dimorphism in honeybees – a modeling approach. Ecology and Evolution 2: 3098-3109.
Linksvayer et al., (2012) Developmental Evolution in Social Insects: Regulatory Networks from Genes to Societies. J. Exp. Zool. Part B-Mol. Dev. Evol. 318B: 159-169.
Maienschein and Laubichler (2010) The Embryo Project: An Integrated Approach to History, Practices, and Social Contexts of Embryo Research. J. Hist. Biol. 43: 1-16.
Laubichler and Maienschein (eds) (2009) Form And Function In Developmental Evolution. Cambridge Studies in Philosophy and Biology.
Laubichler et al. (2005) The Concept of Strategies and John Maynard Smith´s Influence on Theoretical Biology. Biology and Philosophy 20: 1041-1050.
This might be an interesting species for the EvoDevo people.
I saw this article several months ago when I was looking for the diets of vermivore species.
Today I was reading an article of the development of cetacean dentition, and it occurred to me that this rodent might be an interesting species to study. Or perhaps you already knew this one.
“… a new species and genus of shrew-rat from Sulawesi Island, Indonesia that is distinguished from all other rodents by the absence of cheek teeth. Moreover, rather than gnawing incisors, this animal has bicuspid upper incisors, also unique among the more than 2200 species of rodents. Stomach contents from a single specimen suggest that the species consumes only earthworms.”
http://rsbl.royalsocietypublishing.org/content/early/2012/08/21/rsbl.2012.0574
-Kari
Armfield et al. (2013) Development and evolution of the unique cetacean dentition. PeerJ 1:e24 http://dx.doi.org/10.7717/peerj.24
The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Cetaceans are one of the few groups of mammals in which precise occlusion has been secondarily lost. Most toothed whales have an increased number of simple crowned teeth that are similar along the tooth row. Evolution toward these specializations began immediately after the time cetaceans transitioned from terrestrial-to-marine environments. The fossil record documents the critical aspects of occlusal evolution of cetaceans, and allows us to pinpoint the evolutionary timing of the macroevolutionary events leading to their unusual dental morphology among mammals. The developmental controls of tooth differentiation and tooth number have been studied in a few mammalian clades, but nothing is known about how these controls differ between cetaceans and mammals that retain functional occlusion. Here we show that pigs, a cetacean relative with regionalized tooth morphology and complex tooth crowns, retain the typical mammalian gene expression patterns that control early tooth differentiation, expressing Bmp4 in the rostral (mesial, anterior) domain of the jaw, and Fgf8 caudally (distal, posterior). By contrast, dolphins have lost these regional differences in dental morphology and the Bmp4 domain is extended into the caudal region of the developing jaw. We hypothesize that the functional constraints underlying mammalian occlusion have been released in cetaceans, facilitating changes in the genetic control of early dental development. Such major developmental changes drive morphological evolution and are correlated with major shifts in diet and food processing during cetacean evolution.
-Ian
Decoupling the spread of grasslands from the evolution of grazer-type herbivores in South America
Caroline A.E. Strömberg, Regan E. Dunn, Richard H. Madden, Matthew J. Kohn & Alfredo A. Carlini
Nature Communications 4, Article number: 1478
http://www.nature.com/ncomms/journal/v4/n2/full/ncomms2508.html?WT.ec_id=NCOMMS-20130212
The evolution of high-crowned cheek teeth (hypsodonty) in herbivorous mammals during the late Cenozoic is classically regarded as an adaptive response to the near-global spread of grass-dominated habitats. Precocious hypsodonty in middle Eocene (~38 million years (Myr) ago) faunas from Patagonia, South America, is therefore thought to signal Earth’s first grasslands, 20 million years earlier than elsewhere. Here, using a high-resolution, 43–18 million-year record of plant silica (phytoliths) from Patagonia, we show that although open-habitat grasses existed in southern South America since the middle Eocene (~40 Myr ago), they were minor floral components in overall forested habitats between 40 and 18 Myr ago. Thus, distinctly different, continent-specific environmental conditions (arid grasslands versus ash-laden forests) triggered convergent cheek–tooth evolution in Cenozoic herbivores. Hypsodonty evolution is an important example where the present is an insufficient key to the past, and contextual information from fossils is vital for understanding processes of adaptation.
— Jacqueline
I can’t believe this hasn’t been posted yet:
The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals
Science 8 February 2013:
Vol. 339 no. 6120 pp. 662-667
DOI: 10.1126/science.1229237
Maureen A. O’Leary and about 20 others
To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated with fossils, shows that crown clade Placentalia and placental orders originated after the K-Pg boundary. Many nodes discovered using molecular data are upheld, but phenomic signals overturn molecular signals to show Sundatheria (Dermoptera + Scandentia) as the sister taxon of Primates, a close link between Proboscidea (elephants) and Sirenia (sea cows), and the monophyly of echolocating Chiroptera (bats). Our tree suggests that Placentalia first split into Xenarthra and Epitheria; extinct New World species are the oldest members of Afrotheria.
-Ian
That might interest some of you
http://www.pnas.org/content/early/2013/01/09/1220747110.full.pdf?etoc
Best,
Elodie
Oisi, Y., Ota, K. G., Kuraku, S., Fujimoto, S. & Kuratani, S., 2013: Craniofacial development of hagfishes and the evolution of vertebrates.
–Nature: Vol. 493, #7431, pp. 175-0 [doi: 10.1038/nature11794]
http://dx.doi.org/10.1038/nature11794
Abstract:
Cyclostomes, the living jawless vertebrates including hagfishes and lampreys, represent the most basal lineage of vertebrates. Although the monophyly of cyclostomes has been supported by recent molecular analyses, the phenotypic traits of hagfishes, especially the lack of some vertebrate-defining features and the reported endodermal origin of the adenohypophysis, have been interpreted as hagfishes exhibiting a more ancestral state than those of all other vertebrates. Furthermore, the adult anatomy of hagfishes cannot be compared easily with that of lampreys. Here we describe the craniofacial development of a series of staged hagfish embryos, which shows that their adenohypophysis arises ectodermally, consistent with the molecular phylogenetic data. This finding also allowed us to identify a pan-cyclostome pattern, one not shared by jawed vertebrates. Comparative analyses indicated that many of the hagfish-specific traits can be explained by changes secondarily introduced into the hagfish lineage. We also propose a possibility that the pan-cyclostome pattern may reflect the ancestral programme for the craniofacial development of all living vertebrates.
–Mikko