CHIHARAEA AND YAMADAIA (CORALLINALES,RHODOPHYTA) REPRESENT REDUCED AND RECENTLY DERIVED ARTICULATED CORALLINE MORPHOLOGIES1

Phycologists have hypothesized that the diminutive fronds produced by species in the genera Chiharaea and Yamadaia, which are composed of comparatively few genicula and intergenicula, represent morphological intermediates in the evolution of articulated corallines from crustose ancestors. We test this “intermediate frond hypothesis” by comparing rbcL sequences from the generitype species Chiharaea bodegensis and Yamadaia melobesioides to sequences from other coralline genera. We demonstrate that Chiharaea includes two other NE Pacific species, Arthrocardia silvae and Yamadaia americana. Chiharaea species are characterized morphologically by inflated intergenicula and axial conceptacles with apical or acentric pores. Although relationships among the three species are unresolved, Chiharaea bodegensis, C. americana comb. nov., and C. silvae comb. nov. are distinguished from one another by DNA sequences, morphology, habitat, and biogeography. Chiharaea occurs together with Alatocladia, Bossiella, Calliarthron, and Serraticardia macmillanii in a strongly supported clade of nearly endemic north Pacific articulated coralline genera and species that have evolved relatively recently compared to other articulated corallines. In contrast, NW Pacific Yamadaia melobesioides belongs in a clade with Corallina officinalis, the generitype species of Corallina, and therefore we reduce Yamadia to a synonym of Corallina and propose Corallina melobesioides comb. nov. We reject the ‘intermediate frond hypothesis’ and conclude that Chiharaea and Yamadaia are recently derived taxa that evolved from articulated coralline ancestors and represent a reduction in the number of genicula and intergenicula.     

Kelp versus coralline: cellular basis for mechanical strength in the wave‐swept seaweed Calliarthron (Corallinaceae,Rhodophyta)1

Previous biomechanical studies of wave‐swept macroalgae have revealed a trade‐off in growth strategies to resist breakage in the intertidal zone: growing in girth versus growing strong tissues. Brown macroalgae, such as kelps, grow thick stipes but have weak tissues, while red macroalgae grow slender thalli but have much stronger tissues. For example, genicular tissue in the articulated coralline Calliarthron cheilosporioides Manza is more than an order of magnitude stronger than some kelp tissues, but genicula rarely exceed 1 mm in diameter. The great tissue strength of Calliarthron genicula results, at least in part, from a lifelong strengthening process. Here, a histological analysis is presented to explore the cellular basis for mechanical strengthening in Calliarthron genicula. Genicula are composed of thousands of fiber‐like cells, whose cell walls thicken over time. Thickening of constitutive cell walls likely explains why older genicula have stronger tissues: a mature geniculum may be >50% cell wall. However, the material strength of genicular cell wall is similar to the strength of cell wall from a freshwater green alga, suggesting that it may be the quantity—not the quality—of cell wall material that gives genicular tissue its strength. Apparent differences in tissue strength across algal taxa may be a consequence of tissue construction rather than material composition.     

DIFFERENCES IN POLYSACCHARIDE STRUCTURE BETWEEN CALCIFIED AND UNCALCIFIED SEGMENTS IN THE CORALLINE CALLIARTHRON CHEILOSPORIOIDES (CORALLINALES,RHODOPHYTA)1

The articulated coralline Calliarthron cheilosporioides Manza produces segmented fronds composed of calcified segments (intergenicula) separated by uncalcified joints (genicula), which allow fronds to bend and reorient under breaking waves in the wave‐swept intertidal zone. Genicula are formed when calcified cells decalcify and restructure to create flexible tissue. The present study has identified important differences in the main agaran disaccharidic repeating units [→3)‐β‐d ‐Galp (1→ 4)‐α‐l ‐Galp(1→] synthesized by genicular and intergenicular segments. Based on chemical and spectroscopical analyses, we report that genicular cells from C. cheilosporioides biosynthesize a highly methoxylated galactan at C‐6 position with low levels of branching with xylose side stubs on C‐6 of the [→3)‐β‐d ‐Galp (1→] units, whereas intergenicular segments produce xylogalactans with high levels of xylose and low levels of 6‐O‐methyl β‐d ‐Gal units. These data suggest that, during genicular development, xylosyl branched, 3‐linked β‐d ‐Galp units present in the xylogalactan backbones from intergenicular walls are mostly replaced by 6‐O‐methyl‐d‐ galactose units. We speculate that this structural shift is a consequence of a putative and specific methoxyl transferase that blocks the xylosylation on C‐6 of the 3‐linked β‐d ‐Galp units. Changes in galactan substitutions may contribute to the distinct mechanical properties of genicula and may lend insight into the calcification process in coralline algae.     

A PHYLOGENETIC STUDY OF THE CORALLINALES (RHODOPHYTA) BASED ON NUCLEAR SMALL-SUBUNIT rRNA GENE SEQUENCES

Conflicting classifications for the Corallinales were tested by analyzing partial sequences for the nuclear small-subunit ribosomal RNA (SSU) gene of 35 species of coralline algae. Parsimony and likelihood analyses of these data yielded congruent hypotheses that are inconsistent with classifications for the group that include as many as eight subfamilies. Four major clades are resolved within the order, including the early-diverging Sporolithaceae as well as the Melobesioideae and Corallinoideae. The fourth clade, which is supported robustly, includes both nongeniculate and geniculate species classified in the subfamilies Mastophoroideae, Metagoniolithoideae, Lithophylloideae, and Amphiroideae. Molecular and morphological data support the proposal that the latter two subfamilies are sister taxa. Although relationships among some genera are not resolved clearly, the order of branching of taxa among and within the four principal lineages is concordant with paleontological evidence for the group. Relationships inferred among genera within each of the clades is discussed. Seven morphological characters delimiting higher taxonomic groups within the order were combined with the sequence data, analyzed, and optimized onto the resulting tree(s). Except for the presence or absence of genicula, all other characters were found to be phylogenetically informative. Genicula are nonhomologous structures that evolved independently in the Amphiroideae, Corallinoideae, and Metagoniolithoideae. The phenetic practice of separating coralline algae into two categories solely on the basis of the presence or absence of genicula does not accurately reflect the evolutionary history of the group.     

Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries

Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0 MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection’s standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45° bent position is overestimated compared to the upright phantom below 1 MeV by as much as 27% and 82% in the 90° position. The effective dose in the 45° bent position was comparable to that in the 90° bent position for the LLAT and RLAT irradiation geometries. However, the upright phantom underestimates the effective dose to PIMAL in the LLAT and RLAT geometries by as much as 30% at 50 keV.     

Kelp and sea urchin settlement mediated by biotic interactions with benthic coralline algal species

Species interactions can influence key ecological processes that support community assembly and composition. For example, coralline algae encompass extensive diversity and may play a major role in regime shifts from kelp forests to urchin-dominated barrens through their role in inducing invertebrate larval metamorphosis and influencing kelp spore settlement. In a series of laboratory experiments, we tested the hypothesis that different coralline communities facilitate the maintenance of either ecosystem state by either promoting or inhibiting early recruitment of kelps or urchins. Coralline algae significantly increased red urchin metamorphosis compared with a control, while they had varying effects on kelp settlement. Urchin metamorphosis and density of juvenile canopy kelps did not differ significantly across coralline species abundant in both kelp forests and urchin barrens, suggesting that recruitment of urchin and canopy kelps does not depend on specific corallines. Non-calcified fleshy red algal crusts promoted the highest mean urchin metamorphosis percentage and showed some of the lowest canopy kelp settlement. In contrast, settlement of one subcanopy kelp species was reduced on crustose corallines, but elevated on articulated corallines, suggesting that articulated corallines, typically absent in urchin barrens, may need to recover before this subcanopy kelp could return. Coralline species differed in surface bacterial microbiome composition; however, urchin metamorphosis was not significantly different when microbiomes were removed with antibiotics. Our results clarify the role played by coralline algal species in kelp forest community assembly and could have important implications for kelp forest recovery.     

Discordance between morphological and mechanical diversity in the feeding mechanism of centrarchid fishes

Morphological diversity is routinely used to infer ecological variation among species because differences in form underlie variation in functional performance of ecological tasks like capturing prey, avoiding predators, or defending territories. However, many functions have complex morphological bases that can weaken associations between morphological and functional diversification. We investigate the link between these levels of diversity in a mechanically explicit model of fish suction-feeding performance, where the map of head morphology to feeding mechanics is many-to-one: multiple, alternative forms can produce the same mechanical property. We show that many-to-one mapping leads to discordance between morphological and mechanical diversity in the freshwater fish family, the Centrarchidae, despite close associations between morphological changes and their mechanical effects. We find that each of the model's five morphological variables underlies evolution of suction capacity. Yet, the major centrarchid clades exhibit an order of magnitude range in diversity of suction mechanics in the absence of any clear difference in diversity of the morphological variables. This cryptic pattern of mechanical diversity suggests an evolutionary history for suction performance that is unlike the one inferred from comparisons of morphological diversity. Because many-to-one mapping is likely to be common in functional systems, this property of design may lead to widespread discordance between functional and morphological diversity. Although we focus on the interaction between morphology and mechanics, many-to-one mapping can decouple diversity between levels of organization in any hierarchical system.     

Octopuses use a human-like strategy to control precise point-to-point arm movements

One of the key problems in motor control is mastering or reducing the number of degrees of freedom (DOFs) through coordination. This problem is especially prominent with hyper-redundant limbs such as the extremely flexible arm of the octopus. Several strategies for simplifying these control problems have been suggested for human point-to-point arm movements. Despite the evolutionary gap and morphological differences, humans and octopuses evolved similar strategies when fetching food to the mouth. To achieve this precise point-to-point-task, octopus arms generate a quasi-articulated structure based on three dynamic joints. A rotational movement around these joints brings the object to the mouth . Here, we describe a peripheral neural mechanism-two waves of muscle activation propagate toward each other, and their collision point sets the medial-joint location. This is a remarkably simple mechanism for adjusting the length of the segments according to where the object is grasped. Furthermore, similar to certain human arm movements, kinematic invariants were observed at the joint level rather than at the end-effector level, suggesting intrinsic control coordination. The evolutionary convergence to similar geometrical and kinematic features suggests that a kinematically constrained articulated limb controlled at the level of joint space is the optimal solution for precise point-to-point movements.     

Thigmomorphogenesis: On the mechanical properties of mechanically perturbed bean plants

The mechanical properties of control and mechanically perturbed (MP) bean stems ( Phaseolus vulgaris L., ev. Cherokee wax) were compared. The rubbed plants were greatly hardened against mechanical rupture by previous MP. This hardening was due to a dramatic increase in the flexibility of the stems, but not in their stiffness. The MP-plants were able lo bend more than 90° without breaking, whereas the control plants broke after just slight bending. A comparison with other work reveals that different species utilize different tactics for achieving similar resistance to rupture due to mechanical stress.     

Comparison of neutron organ and effective dose coefficients for PIMAL stylized phantom in bent postures in standard irradiation geometries

Neutron dose coefficients for standard irradiation geometries have been reported in International Commission on Radiological Protection (ICRP) Publication 116 for the ICRP Publication 110 adult reference phantoms. In the present work, organ and effective dose coefficients have been calculated for a receptor in both upright and articulated (bent) postures representing more realistic working postures exposed to a mono-energetic neutron radiation field. This work builds upon prior work by Dewji and co-workers comparing upright and bent postures for exposure to mono-energetic photon fields. Simulations were conducted using the Oak Ridge National Laboratory’s articulated stylized adult phantom, “Phantom wIth Moving Arms and Legs” (PIMAL) software package, and the Monte Carlo N-Particle (MCNP) version 6.1.1 radiation transport code. Organ doses were compared for the upright and bent (45° and 90°) phantom postures for neutron energies ranging from 1 × 10^??9 to 20 MeV for the ICRP Publication 116 external exposure geometries—antero-posterior (AP), postero-anterior (PA), and left and right lateral (LLAT, RLAT). Using both male and female phantoms, effective dose coefficients were computed using ICRP Publication 103 methodology. The resulting coefficients for articulated phantoms were compared to those of the upright phantom. Computed organ and effective dose coefficients are discussed as a function of neutron energy, phantom posture, and source irradiation geometry. For example, it is shown here that for the AP and PA irradiation geometries, the differences in the organ coefficients between the upright and bent posture become more pronounced with increasing bending angle. In the AP geometry, the brain dose coefficients are expectedly higher in the bent postures than in the upright posture, while all other organs have lower dose coefficients, with the thyroid showing the greatest difference. Overall, the effective dose estimated for the upright phantom is more conservative than that for the articulated phantom, which may have ramifications in the estimation or reconstruction of radiation doses.     

Adaptations to increasing hydraulic stress: morphology, hydrodynamics and fitness of two higher aquatic plant species

Sessile organisms often exhibit morphological changes in response to permanent exposure to mechanical stimulation (wind or water movements). The adaptive value of these morphological changes (hydrodynamic performance and consequences on fitness) has not been studied extensively, particularly for higher plants submitted to flow stress. The aim was to determine the adaptive value of morphological patterns observed within two higher aquatic plant species, Berula erecta and Mentha aquatica, growing along a natural flow stress gradient. The hydrodynamic ability of each ramet was investigated through quantitative variables (drag coefficient and E-value). Fitness-related traits based on vegetative growth and clonal multiplication were assessed for each individual. For both species, the drag coefficient and the E-value were explained only to a limited extent by the morphological traits used. B. erecta exhibited a reduction in size and low overall plant drag at higher flow velocities, despite high drag values relative to leaf area, due to a low flexibility. The plants maintained their fitness, at least in part, through biomass reallocation: one tall ramet at low velocity, but shorter individuals with many interconnected stolons when flow velocity increased. For M. aquatica, morphological differences along the velocity gradient did not lead to greater hydrodynamic performance. Plant size increased with increasing velocities, suggesting the indirect effects of current favouring growth in high velocities. The fitness-related traits did not demonstrate lower plant fitness for high velocities. Different developmental constraints linked to plant morphology and trade-offs between major plant functions probably lead to different plant responses to flow stress.     

Torsion and Bending in the Neck and Tail of Sauropod Dinosaurs and the Function of Cervical Ribs: Insights from Functional Morphology and Biomechanics

The long necks of sauropods have been subject to many studies regarding their posture and flexibility. Length of the neck varies among groups. Here, we investigate neck posture and morphology in several clades from a mechanical viewpoint. Emphasis is put on comparing sauropod necks and tails with structures in living archosaurs and mammals. Differences in the use made of necks and tails lead to clear-cut differences in the mechanical loads occurring in the same models. Ways of sustaining loads are identified by theoretical considerations. If the observed skeletal structures are suited to resist the estimated loading in a particular posture, this concordance is taken as an argument that this posture or movement was of importance during the life of the individual. Apart from the often-discussed bending in side view, we analyze the often overlooked torsion. Because torsional stresses in a homogenous element concentrate near the periphery, a cylindrical cross section gives greatest strength, and the direction of forces is oblique. In a vertebrate neck, during e.g. shaking the head and twisting the neck, oblique muscles, like the mm. scaleni, if activated unilaterally initiate movement, counterbalance the torsional moments and keep the joints between neck vertebrae in equilibrium. If activated bilaterally, these muscles keep the neck balanced in an energy-saving upright posture. The tendons of the mm. scaleni may have ossified as cervical ribs The long cervical ribs in brachiosaurids and mamenchisaurids seem to have limited flexibility, whereas the shorter cervical ribs in Diplodocidae allowed free movement. The tails of sauropods do not show pronounced adaptation to torsion, and seem to have been carried more or less in a horizontal, extended posture. In this respect, sauropod tails resemble the necks of herbivorous cursorial mammals. These analyses provide an improved understanding of neck use that will be extended to other sauropods in subsequent studies.     

Functional niche partitioning in Therizinosauria provides new insights into the evolution of theropod herbivory

Dietary specialization is generally considered to be a crucial factor in driving morphological evolution across extant and extinct vertebrates. The ability to adapt to a specific diet and to exploit ecological niches is thereby influenced by functional morphology and biomechanical properties. Differences in functional behaviour and efficiency can therefore allow dietary diversification and the coexistence of similarly adapted taxa. Therizinosauria, a group of secondarily herbivorous theropod dinosaurs, is characterized by a suite of morphological traits thought to be indicative of adaptations to an herbivorous diet. Digital reconstruction, theoretical modelling and computer simulations of the mandibles of therizinosaur dinosaurs provides evidence for functional niche partitioning in adaptation to herbivory. Different mandibular morphologies present in therizinosaurians were found to correspond to different dietary strategies permitting coexistence of taxa. Morphological traits indicative of an herbivorous diet, such as a downturned tip of the lower jaw and an expanded postdentary region, were identified as having stress mitigating effects. The more widely distributed occurrence of these purported herbivorous traits across different dinosaur clades suggests that these features also could have played an important role in the evolution and acquisition of herbivory in other groups.     

Masticatory stress and the mechanics of "wishboning" in colobine jaws

Cercopithecoid monkeys experience relatively high strains along the lingual aspect of the mandibular symphysis because of lateral transverse bending of the mandibular corpora ("wishboning") during mastication. Hylander (Am J Phys Anthropol 64 (1984) 1-46; Am Zool 25 (1985) 315-330) demonstrated that the distribution of strains arising from wishboning loads is comprehensible with reference to the mechanics of curved beams. Theory of curved beams suggests that lingual tensile strains are some multiple of labial compressive strains, yet limitations of experimental methods and uncertainty in estimating parameters needed for theoretical calculations have confounded attempts to characterize the magnitude of this disparity of normal strains. We evaluate the theoretical disparity of normal strains in wishboning in comparison to in vitro strains collected under controlled loads for a sample of mandibles representing two colobine species (N = 6). These data suggest that in colobine monkeys, maximum normal lingual strains should be at least twice maximum labial strains. In addition, we reexamine the distribution of symphyseal stress under an assumption of asymmetric bending, a general approach for calculation of stress appropriate for members that lack a plane of symmetry and are bent along an axis that is not coincident with the member's principal axes. Under asymmetric bending in colobine mandibles, the effect of symphyseal inclination on lingual strain is mitigating at the superior transverse torus and exacerbating at the inferior transverse torus. Relative compliance of colobine mandibular bone further supports the hypothesis that the structural and material properties of the colobine mandibular symphysis do not represent a morphological strategy for minimizing masticatory strain.     

Biomimetic Composite Structural T-joints

Biological structural fixed joints exhibit unique attributes,including highly optimized fiber paths which minimize stress concentrations.In addition,since the joints consist of continuous,uncut fiber architectures,the joints enable the organism to transport information and chemicals from one part of the body to the other.To the contrary,sections of man-made composite material structures are often joined using bolted or bonded joints,which involve low strength and high stress concentrations.These methods are also expensive to achieve.Additional functions such as fluid transport,electrical signal delivery,and thermal conductivity across the joints typically require parasitic tubes,wires,and attachment clips.By using the biomimetic methods,we seek to overcome the limitations which are present in the conventional methods. In the present work,biomimetic co-cured composite sandwich T-joints were constructed using unidirectional glass fiber,epoxy resin,and structural foam.The joints were fabricated using the wet lay-up vacuum bag resin infusion method.Foam sandwich T-joints with multiple continuous fiber architectures and sandwich foam thickness were prepared.The designs were tested in quasi-static bending using a mechanical load frame.The significantweight savings using the biomimetic approaches is discussed,as well as a comparison of failure modes versus architecture is described.     

Articulated coralline algae of the genus Amphiroa are highly effective natural inducers of settlement in the tropical abalone Haliotis asinina

The initiation of metamorphosis in marine invertebrates is strongly linked to the environment. Planktonic larvae typically are induced to settle and metamorphose by external cues such as coralline algae (Corallinaceae, Rhodophyta). Although coralline algae are globally abundant, invertebrate larvae of many taxa settle in response to a very limited suite of species. This specificity impacts population structure, as only locations with the appropriate coralline species can attract new recruits. Abalone (Gastropoda, Haliotidae) are among those taxa in which closely related species are known to respond to different coralline algae. Here we identify highly inductive natural cues of the tropical abalone Haliotis asinina. In contrast to reports for other abalone, the greatest proportion of H. asinina larvae are induced to settle and metamorphose (92.8% to 100% metamorphosis by 48 h postinduction) by articulated corallines of the genus Amphiroa. Comparison with field distribution data for different corallines suggests larvae are likely to be settling on the seaward side of the reef crest. We then compare the response of six different H. asinina larval families to five different coralline species to demonstrate that induction by the best inductive cue (Amphiroa spp.) effectively extinguishes substantial intraspecific variation in the timing of settlement.     

Atomistic and coarse-grained analysis of double spectrin repeat units: the molecular origins of flexibility

Spectrin is an ubiquitous protein in metazoan cells, and its flexibility is one of the keys to maintaining cellular structure and organization. Both alpha-spectrin and beta-spectrin polypeptides consist primarily of triple coiled-coil modular repeat units, and two important factors that determine spectrin flexibility are the bending flexibility between two consecutive repeat units and the conformational flexibility of individual repeat units. Atomistic molecular dynamics (MD) simulations are used here to study double spectrin repeat units (DSRUs) from the human erythrocyte beta-spectrin (HEbeta89) and the chicken brain alpha-spectrin (CBalpha1617). From the results of MD simulations, a highly conserved Trp residue in the A-helix of most repeat units that has been suggested to be important in conferring stability to the coiled-coil structures is found not to have a significant effect on the conformational flexibility of individual repeat units. Characterization of the bending flexibility for two consecutive repeats of spectrin via atomistic simulations and coarse-grained (CG) modeling indicate that the bending flexibility is governed by the interactions between the AB-loop of the first repeat unit, the BC-loop of the second repeat unit and the linker region. Specifically, interactions between residues in these regions can lead to a strong directionality in the bending behavior of two repeat units. The biological implications of these finding are discussed.     

Taxonomic and biostratigraphical re-assessments of Subterraniphyllum Elliott (Corallinales, Rhodophyta)

A taxonomic and biostratigraphical re‐assessment of Subterraniphyllum Elliott (Corallinales, Rhodophyta) is presented. Results from studies of the type collection and of newly collected material from north‐eastern Italy and northern Slovenia have shown that this taxon is not a geniculate coralline red alga as originally suggested by Elliott and most subsequent authors. Vegetatively, Subterraniphyllum most closely resembles certain living members of the Corallinales; however, the phenetic and phylogenetic relationships of Subterraniphyllum to other Corallinales cannot be determined with greater certainty. The exclusion of Subterraniphyllum from any group of Corallinaceae with genicula is based on unequivocal evidence that branch formation does not involve the occurrence of genicula. Subterraniphyllum seems to be restricted to the Oligocene. Reports of occurrences in Upper Eocene and Lower Miocene sediments cannot be substantiated. Subterraniphyllum, however, cannot be considered a useful stratigraphical marker until further data on its occurrence in well‐dated carbonate sequences are acquired. This study illustrates the problems associated with placing fossil coralline algal specimens into geniculate genera without the preservation of relevant morphological characters. This is especially true in the absence of the careful assessment of fossil material with respect to current taxonomic concepts of geniculate coralline genera, all of which are based on studies of living species. According to the current concepts for geniculate coralline genera, the placing of fossil specimens into geniculate genera without appropriate evidence must be avoided by grouping all potentially geniculate fragments under the informal group ‘Geniculate sensu lato’. Furthermore, for all those many fossil specimens where unequivocal evidence is not present, it is possible to utilize ‘form genera’ based on characters that are normally preserved. This leads to creating a consistent, workable system of applying names to most fossil corallines so that they can be reliably used in relation to stratigraphical and palaeoecological studies.