Post by creature386 on Apr 11, 2015 21:23:56 GMT 5
Darwinius masillae
Temporal range: Eocene (about 47 MYA)[1]
Location: Germany, Messel pit. Back then it was very likely a para-tropical rain forrest[1]
Life restoration of Darwinius masillae, Sketches are by Bogdan Bocianowski[2]
Scientific classification:
Primates
Euprimates
Notharctidae
Cercamoniinae
Darwinius
D. masillae[3]
Etymology:
The genus name honors the British biologist Charles Darwin he had his 200th birthday when the description of Darwinius was written. Masilla means Messel in the Codex of the Lorsch monastery, 800 AD.[1]
Holotype specimen:
Plate A and B of the specimen compared.[4]
The specimen was found by private collectors in 1983 and divided into two plates which were sold. Plate B (WDC-MG-210) got altered (as noticed by Franzen JL in 2000) and sold to a private museum in Wyoming, while plate A (PMO 214.214) arrived in the Natural History Museum of the University of Oslo (Norway). Plate A was immediately recognized as the counterpart of plate B after it got revealed for study.[5] The specimen is described as a juvenile. The presence of a few erupted molars indicates that it had just passed infancy before it died. It is also viewed as a female on the basis of the lack of a baculum (penis bone). This bone is commonly preserved in male primates and the probability of having it preserved in a that complete male skeleton is very high.[6]
Description and paleobiology:
Darwinius masillae is known from good fossil material. The holotype specimen is exceptionally preserved. With its soft tissue outlines and digestive tract contents, it is one of the most complete prehistoric primate fossils.[5] It is believed that the specimen sank on the bottom of a lake, landed on the back and came to rest on the side without any activity from predators or scavengers before it got buried.[7] The cranium of D. masillae shows large eye orbits, a short rostrum and a steep face.[8] The teeth are typical for a juvenile primate, given that the permanent dentition had just begun to mineralize and there is evidence for deciduous (non-permanent) teeth in the jaw.[9] The backbone of D. masillae was gently curved as seen in plate 1 and not as stretched out as seen in plate 2. The stretched out backbone was part of the altering and is therefore fake. The skeleton is 58 cm long, the head-body length is 24 cm.[10] The holotype probably died at an age of 3 years, the lifespan of D. masillae could have been up to 20 years.[6] An adult could have attained a head-body length of 28 cm.[11]
Principle components analysis (PCA) of trunk and limb proportions in extant Lemuroidea, Lorisoidea, Tarsioidea, and Ceboidea. PC-I is a regression for body mass, the PC-II regression contrasts thorax length and foot length (relevant for determining locomotion) and PC-III contrasts lumbus length and scapula length (also for determining locomotion). The abbreviations refer to primate family names.[11]
Estimating the body mass of the Darwinius masillae holotype is quite challenging. Different methods that use skull length, tooth size and limb segments yield a range of 385 to 1,700 g. 485 g, as regressions with PC-I scores that use extant relatives yield, appears to be the best result.[10] Using that weight and assuming that the holotype specimen died at 85-90% of its maximum body length and 60% of her maximum weight,[12] an adult D. masillae can be estimated at 650-900 g.[11]
As D. masillae falls in the middle of the climbing-leaping regressions you can see in the principle components analysis, it is save to assume that it was not specialized for slow climbing nor for leaping.[12]
D. masillae is seen as a herbivore, given that its digestive tract includes leaves and fruits, but no insects. Also, the estimated weight for D. masillae lies above the threshold value for herbivorous primates.[11] Looking at the size of the orbits, the animal could have been nocturnal.[13]
Phylogenetic position:
Phylogenetic position of Darwinius according to the description paper.[14]
Darwinius masillae was a very basal primate that had features Strepsirrhini ("moist nose monkeys") and Haplorhini ("dry nose monkeys"), but closer to Haplorhini, as the cladogram indicates. The classification is based on a comparison of 30 traits from both groups with those of Darwinius.[15] The table can be seen here:[5]
A more recent analysis used 360 traits instead of merely 30 (this is low for a phylogenetic analysis) and contradicts the results of Franzen et al.. Instead, it postulates the classification you can see above.[3]
Media:
8:22-9:40 of my 11th Life before man episode deals with Darwinius and includes some more pictures from the description paper for those who don't want to read it.
The video calls the holotype Ida because it is called like that in the media quite often:
www.newscientist.com/article/dn18007-missing-link-ida-lacks-evolutionary-insights.html#.VSlIdiig1sZ
Description paper:
Franzen JL, Gingerich PD, Habersetzer J, Hurum JH, von Koenigswald W, et al. (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE 4(5): e5723. p. 1-27 doi:10.1371/journal.pone.0005723
Footnotes:
[1] Franzen et al. p. 5
[2] Franzen et al. Figure S6
[3] Erik R. Seiffert, Jonathan M. G. Perry, Elwyn L. Simons & Doug M. Boyer Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates Nature 461, 1118-1121 (22 October 2009) 10.1038/nature08429
[4] Franzen et al. p. 2
[5] Franzen et al. p. 1
[6] Franzen et al. p. 18-20
[7] Franzen et al. p. 18
[8] Franzen et al. p. 8
[9] Franzen et al. p. 10
[10] Franzen et al. p. 12
[11] Franzen et al. p. 22-23
[12] Franzen et al. p. 21
[13] Franzen et al. p. 23
[14] Franzen et al. Figure S7
[15] Franzen et al. p. 23-24
Temporal range: Eocene (about 47 MYA)[1]
Location: Germany, Messel pit. Back then it was very likely a para-tropical rain forrest[1]
Life restoration of Darwinius masillae, Sketches are by Bogdan Bocianowski[2]
Scientific classification:
Primates
Euprimates
Notharctidae
Cercamoniinae
Darwinius
D. masillae[3]
Etymology:
The genus name honors the British biologist Charles Darwin he had his 200th birthday when the description of Darwinius was written. Masilla means Messel in the Codex of the Lorsch monastery, 800 AD.[1]
Holotype specimen:
Plate A and B of the specimen compared.[4]
The specimen was found by private collectors in 1983 and divided into two plates which were sold. Plate B (WDC-MG-210) got altered (as noticed by Franzen JL in 2000) and sold to a private museum in Wyoming, while plate A (PMO 214.214) arrived in the Natural History Museum of the University of Oslo (Norway). Plate A was immediately recognized as the counterpart of plate B after it got revealed for study.[5] The specimen is described as a juvenile. The presence of a few erupted molars indicates that it had just passed infancy before it died. It is also viewed as a female on the basis of the lack of a baculum (penis bone). This bone is commonly preserved in male primates and the probability of having it preserved in a that complete male skeleton is very high.[6]
Description and paleobiology:
Darwinius masillae is known from good fossil material. The holotype specimen is exceptionally preserved. With its soft tissue outlines and digestive tract contents, it is one of the most complete prehistoric primate fossils.[5] It is believed that the specimen sank on the bottom of a lake, landed on the back and came to rest on the side without any activity from predators or scavengers before it got buried.[7] The cranium of D. masillae shows large eye orbits, a short rostrum and a steep face.[8] The teeth are typical for a juvenile primate, given that the permanent dentition had just begun to mineralize and there is evidence for deciduous (non-permanent) teeth in the jaw.[9] The backbone of D. masillae was gently curved as seen in plate 1 and not as stretched out as seen in plate 2. The stretched out backbone was part of the altering and is therefore fake. The skeleton is 58 cm long, the head-body length is 24 cm.[10] The holotype probably died at an age of 3 years, the lifespan of D. masillae could have been up to 20 years.[6] An adult could have attained a head-body length of 28 cm.[11]
Principle components analysis (PCA) of trunk and limb proportions in extant Lemuroidea, Lorisoidea, Tarsioidea, and Ceboidea. PC-I is a regression for body mass, the PC-II regression contrasts thorax length and foot length (relevant for determining locomotion) and PC-III contrasts lumbus length and scapula length (also for determining locomotion). The abbreviations refer to primate family names.[11]
Estimating the body mass of the Darwinius masillae holotype is quite challenging. Different methods that use skull length, tooth size and limb segments yield a range of 385 to 1,700 g. 485 g, as regressions with PC-I scores that use extant relatives yield, appears to be the best result.[10] Using that weight and assuming that the holotype specimen died at 85-90% of its maximum body length and 60% of her maximum weight,[12] an adult D. masillae can be estimated at 650-900 g.[11]
As D. masillae falls in the middle of the climbing-leaping regressions you can see in the principle components analysis, it is save to assume that it was not specialized for slow climbing nor for leaping.[12]
D. masillae is seen as a herbivore, given that its digestive tract includes leaves and fruits, but no insects. Also, the estimated weight for D. masillae lies above the threshold value for herbivorous primates.[11] Looking at the size of the orbits, the animal could have been nocturnal.[13]
Phylogenetic position:
Phylogenetic position of Darwinius according to the description paper.[14]
Darwinius masillae was a very basal primate that had features Strepsirrhini ("moist nose monkeys") and Haplorhini ("dry nose monkeys"), but closer to Haplorhini, as the cladogram indicates. The classification is based on a comparison of 30 traits from both groups with those of Darwinius.[15] The table can be seen here:[5]
A more recent analysis used 360 traits instead of merely 30 (this is low for a phylogenetic analysis) and contradicts the results of Franzen et al.. Instead, it postulates the classification you can see above.[3]
Media:
8:22-9:40 of my 11th Life before man episode deals with Darwinius and includes some more pictures from the description paper for those who don't want to read it.
The video calls the holotype Ida because it is called like that in the media quite often:
www.newscientist.com/article/dn18007-missing-link-ida-lacks-evolutionary-insights.html#.VSlIdiig1sZ
Description paper:
Franzen JL, Gingerich PD, Habersetzer J, Hurum JH, von Koenigswald W, et al. (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE 4(5): e5723. p. 1-27 doi:10.1371/journal.pone.0005723
Footnotes:
[1] Franzen et al. p. 5
[2] Franzen et al. Figure S6
[3] Erik R. Seiffert, Jonathan M. G. Perry, Elwyn L. Simons & Doug M. Boyer Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates Nature 461, 1118-1121 (22 October 2009) 10.1038/nature08429
[4] Franzen et al. p. 2
[5] Franzen et al. p. 1
[6] Franzen et al. p. 18-20
[7] Franzen et al. p. 18
[8] Franzen et al. p. 8
[9] Franzen et al. p. 10
[10] Franzen et al. p. 12
[11] Franzen et al. p. 22-23
[12] Franzen et al. p. 21
[13] Franzen et al. p. 23
[14] Franzen et al. Figure S7
[15] Franzen et al. p. 23-24