Lobopodians, a nonmonophyletic assemblage of worm-shaped soft-bodied animals most closely related to arthropods, show two major morphotypes: long-legged and short-legged forms. The morphotype with ...stubby, conical legs has a long evolutionary history, from the early Cambrian 1 through the Carboniferous 2, 3, including the living onychophorans and tardigrades 4–6. Species with tubular lobopods exceeding the body diameter have been reported exclusively from the Cambrian 7–12; the three-dimensionally preserved Orstenotubulus evamuellerae from the uppermost middle Cambrian “Orsten” (Sweden) is the youngest long-legged lobopodian reported thus far 8. Here we describe a new long-legged lobopodian, Carbotubulus waloszeki gen. et sp. nov., from Mazon Creek, Illinois, USA (∼296 million years ago) 13. This first post-Cambrian long-legged lobopodian extends the range of this morphotype by about 200 million years. The three-dimensionally preserved specimen differs significantly from the associated short-legged form Ilyodes inopinata 2, of which we also present new head details. The discovery of a Carboniferous long-legged lobopodian provides a more striking example of the long-term survival of Cambrian morphotypes than, for example, the occurrence of a Burgess Shale-type biota in the Ordovician of Morocco 14 and dampens the effect of any major extinction of taxa at the end of the middle Cambrian 15, 16.
► The first post-Cambrian long-legged lobopodian was found in the late Carboniferous ► It is about 200 million years younger than other long-legged lobopodians ► This finding is an extreme example of a long-term survival of a Cambrian morphotype
Putting heads together Briggs, Derek E. G.; Parry, Luke A.
Science (American Association for the Advancement of Science),
11/2022, Volume:
378, Issue:
6622
Journal Article
Peer reviewed
Cambrian fossils reveal ancestry of the segmented brain in arthropods
The most species-rich group of animals today and during the Cambrian 539 million to 485 million years (Ma) ago is the arthropods, ...which include shrimps, horseshoe crabs, scorpions, centipedes, and insects. These animals are characterized by their exoskeleton, jointed limbs, and repeated body segments. A notable feature of arthropods is their head appendages, which have adapted to a diversity of functions, from sensing the environment to capturing prey. Difficulties in interpreting the homology of head appendages in living and fossil arthropod groups the arthropod head problem (
1
,
2
) have complicated attempts to resolve their interrelationships. Understanding how these appendages are innervated by the brain, information rarely preserved in fossils, is crucial for identifying their evolutionary origins. On page 905 of this issue, Strausfeld
et al.
(
3
) report new details in the head of the lobopodian
Cardiodictyon catenulum
, preserved in 518 million-year-old Cambrian rocks near Kunming, China, that reveal the ancestry of the arthropod segmented brain.
•Comparison of fossil eumelanin reveals constraints on preservation.•Alteration of eumelanin is primarily due to maturation.•Alteration of eumelanin is largely independent of age and diagenetic ...mineralization.•Alteration of eumelanin is not accompanied by a change in granule morphology.
Melanins are polymeric phenolic pigments classified into two groups based on their chemical structures and molecular precursors: eumelanin (brown–black) and pheomelanin (yellow–red). Eumelanin is highly resilient and has a proven fossil record, extending back at least ∼200Ma. It is widespread in the biological world, occurring in fungi, the ink sacs of cephalopods, the feathers of birds, and the hair, skin, eyes, brain and inner ears of mammals. Although the presence and chemical attributes of fossil eumelanin have been documented, there are few data constraining its long term survival. Here we use a diversity of analytical techniques to compare the chemistry and morphology of fossilized cephalopod ink from three deposits of similar age and lithology, but different maturation histories. We demonstrate that the chemistry of eumelanin begins to alter at the onset of the oil window and is largely independent of age. The decrease in surviving melanin is accompanied by an increase in the relative abundance of organic macromolecular material (kerogen) but, critically for the correct interpretation of fossils, is not accompanied by a consistent change in granule morphology.
Briggs cites that amber, which is fossilized tree resin, is full of surprises. The great majority of creatures in amber are insects, and they often preserve the finest 3D details. This is an ...important consideration when we use the evidence of fossils entombed in amber to interpret terrestrial environments and ecosystems of the past. Amber is an unparalleled source of information on ancient insects. It contributes to our knowledge of extinct forms, the significance of fossils for phylogenetic studies, the geographic distribution and diversity of insects in the past, and the age of different insect groups.
Pentastomids (tongue worms) are worm-like arthropods known today from ∼140 species 1. All but four are parasitic on vertebrates. Their life cycle typically involves larval development in an ...intermediate host followed by maturation in the respiratory tract of a definitive terrestrial host. Fossil pentastomids are exceedingly rare and are known only from isolated juveniles 2–6. The identity of the possible hosts of fossil pentastomids and the origin of their lifestyle have generated much debate. A new, exceptionally preserved species, described based on adults from 425-million-year-old marine rocks, is the only known fossil pentastomid associated with a host, in this case a species of ostracod crustacean. The pentastomids are preserved near eggs within the ostracod and also, uniquely for any fossil or living pentastomid, are attached externally to the host. This discovery affirms the origin of pentastomids as ectoparasitic on marine invertebrates. The terrestrialization of pentastomids may have occurred in parallel with the vertebrate invasion of land.
•A 425-million-year-old pentastomid is the first adult example from the fossil record•It is the only known fossil pentastomid preserved with its host•Uniquely among pentastomids, some specimens are attached to the host externally•Living pentastomids may have originated as ectoparasites on marine invertebrates
Most Recent pentastomids are parasitic on vertebrates. Siveter et al. describe a 425-million-year-old pentastomid—the first fossil adult examples and the only known fossil pentastomid preserved with its (ostracod) host, including, uniquely, some specimens attached externally. Pentastomids may have originated as ectoparasites on marine invertebrates.
The last common ancestor of animals is thought to have been small and soft-bodied and therefore would have required special conditions for its preservation.Limited availability of these conditions in ...the Neoproterozoic could explain the discrepancy between molecular clock predictions for the timing of animal origins and the fossil record of animals.We assess the availability of these conditions, particularly those of Burgess Shale-type, which are known to preserve animals with tissues of varied composition.Burgess Shale-type conditions are rarely associated with Neoproterozoic fossil biotas, but in the few assemblages with these conditions, dated to 789 million years ago or older, no animals have been identified, suggesting they had not evolved by this time.This provides a soft maximum age constraint on crown group animals of 789 million years ago.
Estimates for animal antiquity exhibit a significant disconnect between those from molecular clocks, which indicate crown animals evolved ∼800 million years ago (Ma), and those from the fossil record, which extends only ∼574 Ma. Taphonomy is often held culpable: early animals were too small/soft/fragile to fossilise, or the circumstances that preserve them were uncommon in the early Neoproterozoic. We assess this idea by comparing Neoproterozoic fossilisation processes with those of the Cambrian and its abundant animal fossils. Cambrian Burgess Shale-type (BST) preservation captures animals in mudstones showing a narrow range of mineralogies; yet, fossiliferous Neoproterozoic mudstones rarely share the same mineralogy. Animal fossils are absent where BST preservation occurs in deposits ≥789 Ma, suggesting a soft maximum constraint on animal antiquity.
Ostracod crustaceans originated at least 500 Ma ago. Their tiny bivalved shells represent the most species-abundant fossil arthropods, and ostracods are omnipresent in a wide array of freshwater and ...marine environments today and in the past.
gen. et sp. nov. from the Herefordshire Silurian Lagerstätte (~430 Ma) in the Welsh Borderland, UK, is one of only a handful of exceptionally preserved ostracods (with soft parts as well as the shell) known from the Palaeozoic. A male specimen provides the first evidence of the appendages of Binodicopina, a major group of Palaeozoic ostracods comprising some 135 Ordovician to Permian genera. The appendage morphology of
, but not its shell, indicates that binodicopes belong to Podocopa. The discovery that the soft-part morphology of binodicopes allies them with podocopes affirms that using the shell alone is an unreliable basis for classifying certain fossil ostracods, and knowledge of soft-part morphology is critical for the task. Current assignment of many fossil ostracods to higher taxa, and therefore the evolutionary history of the group, may require reconsideration.
Brood care in a Silurian ostracod Siveter, David J; Siveter, Derek J; Sutton, Mark D ...
Proceedings of the Royal Society. B, Biological sciences,
02/2007, Volume:
274, Issue:
1609
Journal Article
Peer reviewed
Open access
An exceptionally preserved new ostracod crustacean from the Silurian of Herefordshire, England, preserves eggs and possible juveniles within its carapace, providing an unequivocal and unique view of ...parental brood care in the invertebrate fossil record. The female fossil is assigned to a new family and superfamily of myodocopids based on its soft-part anatomy. It demonstrates a remarkably conserved egg-brooding reproductive strategy within these ostracods over 425 Myr. The soft-tissue anatomy urges extreme caution in classifying 'straight-hinged' Palaeozoic ostracods based on the carapace alone and fundamentally questions the nature of the shell-based Palaeozoic ostracod record.
The colour of fossil feathers Vinther, Jakob; Briggs, Derek E.G; Prum, Richard O ...
Biology letters (2005),
10/2008, Volume:
4, Issue:
5
Journal Article
Peer reviewed
Open access
Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded ...that fossil feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1-2 μm long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil feathers are preserved as melanosomes, and that the distribution of these structures in fossil feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.
An exceptionally preserved new ostracod crustacean from the Silurian of Herefordshire, UK, represents only the third fully documented Palaeozoic ostracod with soft-part preservation. Appendages, ...gills, gut system, lateral compound eyes and even a medial eye with a Bellonci organ are preserved, allowing assignment of the fossil to a new genus and species of cylindroleberidid myodocope (Myodocopida, Cylindroleberididae). The Bellonci organ is recorded for the first time in fossil ostracods. The find also represents a rare occurrence of gills in fossil ostracods and confirms the earliest direct evidence of a respiratory-cum-circulatory system in the group. The species demonstrates remarkably conserved morphology within myodocopes over a period of 425 Myr. Its shell morphology more closely resembles several families of myodocopes other than the Cylindroleberididae, especially the Cypridinidae and Sarsiellidae, thus questioning the utility of the carapace alone in establishing the affinity of fossil ostracods.
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