Makanyaga
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- Sep 28, 2007
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Mammal-like crocodile fossil found in East Africa, scientists report
Ohio University-led study uncovers skeleton of unusual Cretaceous creature
Ohio University-led study uncovers skeleton of unusual Cretaceous creature
If you only looked at the teeth, you wouldnt think this was a crocodile. You would wonder what kind of strange mammal or mammal-like reptile it is, said study lead author Patrick OConnor, associate professor of anatomy in the Ohio University College of Osteopathic Medicine.
The scientists describe the new species of notosuchian crocodyliform as a small animalits head would fit in the palm of your hand, OConnor saidthat wasnt as heavily armored as other crocodiles, except along the tail. Other aspects of its anatomy suggest it was a land-dwelling creature that likely feasted on insects and other small animals to survive.
OConnor and his international research team, funded by the U.S. National Science Foundation and the National Geographic Society, found a complete specimen of the crocodile in 2008, and now have recovered portions of seven different individuals in southwestern Tanzania. The tooth row with molar-like teeth initially puzzled many experts. Other ancient and living crocodiles typically boast relatively simple, conical teeth that serve to seize and tear prey; they swallow flesh in large chunks.
The molar teeth of the new species, named Pakasuchus (Paka is the Ki-Swahili name for cat and souchos is Greek for crocodile), possessed shearing edges for processing food, similar in form to the teeth of some mammalian carnivores.
Once we were able to get a close look at the teeth, we knew we had something new and very exciting, OConnor said.
The research teams discovery that the animals had heavily plated tails but relatively unarmored bodies with gracile limbs suggests that the creatures were quite mobile. They probably actively foraged on land, unlike water-dwelling crocodiles.
The new species isnt a close relative of modern crocodilians, but is a member of a very successful side branch of the crocodyliform lineage that lived during the Mesozoic Era, OConnor said.
While the specimens of the newly discovered animal and its close relatives are unusual, the study suggests that the creatures were abundant during the middle Cretaceous, from around 110 million until 80 million years ago.
The more exploration we do, the more we push the boundaries on what we thought we knew about animal life on the planet, OConnor noted.
Based on other fossils discovered as part of the Rukwa Rift Basin Project, Pakasuchus lived alongside large, plant-eating sauropod and predatory theropod dinosaurs, other types of crocodiles, turtles and various kinds of fishes.
We suspect that notosuchians were very successful in the southern hemisphere because they were exploiting a certain ecological niche, one in which they were able to successfully compete with other small-bodied, terrestrial animals, OConnor said. This is an environment that was quite different from what we typically think of for crocodiles.
Little is known about the vegetation during this time period, but detailed sedimentological analysis of the Rukwa Rift Basin shows that the landscape was dominated by a large, long-lived river system with multiple, crisscrossing channels and low-relief vegetated floodplains in between that apparently supported a relatively rich vertebrate fauna, said Eric Roberts, an assistant professor of geology at James Cook University who collaborated on the research while at the Southern Utah University.
During much of the Cretaceous Period, Afro-Arabia, along with India, Madagascar, Antarctica, Australia and South America, were joined together as the southern supercontinent Gondwana. Relatively few Cretaceous-age mammals have been recovered from this part of the world, and most of those discovered dont appear to be related to modern mammals. Notosuchian crocodyliforms may have taken up residence in a mammalian niche in Gondwana during the Cretaceous Period.
One of the reasons were working in different parts of the southern hemisphere, including Africa and Antarctica, is that not as much exploration has been done in these locales. We are still piecing together the puzzle of what animal life was like in these places, OConnor said. Perhaps we just havent found the mammals yet.
Collaborators on the study include Nancy Stevens and Ryan Ridgely of Ohio University; Joseph Sertich of Stony Brook University; Eric Roberts of James Cook University; Michael Gottfried of Michigan State University; Tobin Hieronymus of the Northeastern Ohio Universities College of Medicine; Zubair Jinnah of the University of the Witwatersrand, South Africa; Sifa Ngasala of Michigan State University and the University of Dar es Salaam in Tanzania; and Jesuit Temba of the Tanzanian Antiquities Unit.
For more information about the project: http://www.oucom.ohiou.edu/rukwa/index.htm.
More links that you might find interesting:
nsf.gov - These Crocs Are Made for Biting! - Special Report
BBC - Homepage
Fossil "Cat Crocodile" Had Mammal-like Teeth
Ripoti ya wanasayansi Juu ya Uvumbuzi mpya wa Masalia ya Mamba-kama-mamalia toka Afrika ya Mashariki
Utafiti ulioongozwa na timu toka Chuo Kikuu cha Ohio wavumbua masalia yasiyo ya kawaida ya kiumbe aliyeishi katika kipindi cha Creataceous
Kwa kutazama meno tu, ni vigumu kutambua moja kwa moja kuwa masalia haya ni ya mamba. Ungestaajabishwa mno na aina hiyo ya mammalia au tuseme mammalia afananae na reptalia, ameeleza mtafiti kiongozi Patrick OConnor, Mhaziri Mwandamizi wa mifupa wa Chuo Kikuu cha Ohio Idara ya Tiba za Mifupa.
Wanasayansi hao wanamwelezea kiumbe huyo mpya kujulikana ajulikanaye kama notosuchian crocodyliform kuwa ni mdogo kwa umbo kichwa chake kinaenea katika kiganja cha mkono wako, alielezea OConnor
Oconnor na kundi lake la watafiti toka mataifa mbalimbali, wakifadhiliwa na, U.S. National Science Foundation na the National Geographic Society, mwaka 2008 walifanikiwa kuvumbua fuvu kamili la aina ya mamba na mpaka sasa wameshafanikiwa kufukua yapata sehemu saba za aina nyingine tofauti tofauti za jamii zingine za mamba toka nyanda hizi za juu za Tanzania. Awali aina ya meno ya kusaga chakula ya mamba hawa yalipovumbuliwa yaliwachanganya watafiti wengi. Kwa kawaida aina nyinginezo za mamba kama hawa wa kale huwa na meno ya kusagia yaliyochongoka, wanayotumia kukamata na kurarua mawindo; kisha humeza mapande makubwa bila kusaga. Hii ni tofauti na aina hii mpya ya mamba waliovumbuliwa katika tafiti hizi.
Meno ya kusagia ya jamii hii ya mamba, aitwaye Pakasuchus (Paka ni kwa kumfananisha na paka na souchos ni kiyunani kikimaanisha mamba), yana ncha za kulegeza na kulainisha chakula, kama ilivyo kwa mamalia wala nyama.
Baada ya uchunguzi wa kina wa aina ya meno ya mamba hao, tukatambua tumevumbua aina ya kipekee nay a kufurahisha ya mamba, alisema Oconnor.
Uvumbuzi huu wa timu hii ya watafiti juu ya wanyama waliokuwa na magamba mazito mkiani huku ingali sehemu ya mwili iliyobaki ikiwa na bila ya magamba mengi na miguu ya kipole ikiashiria utembezi wao. Pia walikuwa wakitumia viganja kushikia kinyume kabisa na mamba waishio majini.
Aina hii mpya ya viumbe iliyogunduliwa si ya kufanana zaidi na aina ya mamba tuwaonao leo hii, ila inasadikika kuwa katika kundi la aina ya mamba waliofanikiwa sana katika kipindi hicho cha Mesozoic, alisema OConnor.
Japo kwa ssa na muonekano wa aina hiyo ya wanyama inaonekana ya kushangaza, utafiti umeonyesha kuwa viumbe hao walikuwa wengi na wa kawaida mno kipindi hicho cha katikati ya Cretaceous kati ya miaka milioni 110 na 80 iliyopita.
Kadiri tunavyofanya utafiti na kudundua aina mbalimbali za viumbe wa kale ndivyo uelewa wetu wa sayari yetu na viumbe wake walioishi nyakati hizo tunavyozidi kuzitambua aligusia OConnor.
Kwa mujibu wa masalia mengine ya viumbe waliopatikana katika Mradi wa Utafiti wa Bonde la Ufa la Rukwa (Rukwa Rift Basin Project), Pakasuchus aliishi pamoja na Saurop wakubwa wala mimea na theropod dinoso wala wnyama, aina nyingine za mamba, kobe na aina mbalimbali za samaki.
Tunasadiki kwa mujibu wa tafiti notosuchiani walikuwa wenye mafanikio makubwa kusini mwa Ikweta kwa kuwa kiikolojia walishika maeneo maalumu, mojawapo ikiwa ni mle walimoweza kushindana na viumbe wengine wadogo kwa mwili waishio nchi kavu, alisema OConnor. Na haya ndiyo mazingira ambayo yalikuwa ya aina yake mno ukilinganisha na tuliyoyazoea.
Kuhusu mimea iliyokuwepo kipindi hichi si mengi yanafahamika, ila kwa mujibu wa utafiti wa kina wa kisedimentolojia wa bonde la ufa la Rukwa unaonyesha kuwa bonde lilitawaliwa na mito mikubwa ya kudumu, na mabonde yenye kutakatana kwenye nyanda za chini iliyojaa mimea na kwa aina kutawaliwa na wanyama wenye uti wa mgongo, alisema Eric Roberts, Mhadhiri Msaidizi wa Jiolojia toka Chuo Kikuu cha James Cook ambaye ni moja ya washiriki wakuu wa utafiti huu wakati akiwa katika Chuo Kikuu cha Southern Utah.
Katika kipindi cha Cretaceous, maeneo yafuatayo Afro-Arabia, along with India, Madagascar, Antarctica, Australia na Amerika ya Kusini, yalikuwa bado yameunagana yakiunda bara kubwa la kusini lililojulikana kama Gondwana. Kwa ujumla ni mamalia wachache sana waliovumbuliwa toka maeneo haya ya dunia na wachache waliopatikana wanamuonekano tofauti sana na wale wa leo hii. Aina ya mamba wajulikanao kama Notosuchiani yawezekana waliwazibiti kushamiri na kushika ,maeneo ya mamalia kipindi cha Cretaceous huko Gondwana.
Moja ya sababu zinazopelekea tufanye kazi kusini mwa Ikweta, ikiwemo Afrika na Antarctica, ni uhaba wa tafiti zilizofanyika tayari katika maeneo haya. Hivyo bado tunaendelea kutafiti kutegua kitendawili cha jinsi gani maisha ya wanyama yalivyokuwa sehemu hizo, anaeleza OConnor. "Huenda ni kwamba bado hatujampata aina halisi ya mammalia."
Washiriki wakuu wa utafiti ni pamoja na: Nancy Stevens and Ryan Ridgely wa Chuo Kikuu cha Ohio - Marekani; Joseph Sertich wa Chuo Kikuu cha Stony Brook - Marekani; Eric Roberts wa Chuo Kikuu cha James Cook - Australia; Michael Gottfried wa Chuo Kikuu cha Michigan State - Marekani; Tobin Hieronymus wa Idara ya Tiba ya Chuo Kikuu cha Northeastern Ohio - Marekani; Zubair Jinnah wa Chuo Kikuu cha Witwatersrand - Afrika ya Kusini; Sifa Ngasala wa Chuo Kikuu cha Michigan State University - Marekani and Chuo Kikuu cha Dar es Salaam - Tanzania; na Jesuit Temba Idara ya Mambo ya Kale ya Tanzanian.
Kwa maelezo zaidi juu ya mradi huu wa utafiti, tembelea tovuti hii: http://www.oucom.ohiou.edu/rukwa/index.htm.
