Feed Marks Research Articles

Fossil evidence of lichen grazing from Palaeogene amber

Lichens are important in many modern terrestrial ecosystems, but their fossil record has been very sparse. This has limited the chances for finding any evidence of their interactions with animals in past ecosystems. Recently, the fossil record of lichens has improved significantly with the discovery of numerous new inclusions from European Palaeogene ambers. Here, we report the first fossil evidence of animal–lichen interactions from one new fossil from Bitterfeld amber of central Germany. A foliose fossil lichen, possibly belonging to the Physciaceae, exhibits three feeding marks and co-preserved invertebrate faecal pellets. To gain insights into this Palaeogene lichen-invertebrate interaction, we compared the fossil grazing damage and faecal pellets to those obtained from several extant lichen feeders, including mites, collembolans, psocopterans, coleopteran larvae and gastropods. The results of the grazing experiments suggest that gastropods and mites most likely caused the feeding marks preserved in the fossil lichen.

Investigating hole making performance of Al 2024-T3/Ti-6Al-4V alloy stacks: A comparative study of conventional drilling, peck drilling and helical milling

This work reports a comparative study on different hole making methods, namely conventional drilling, peck drilling and helical milling, for Al 2024-T3/Ti-6Al-4V stacks in aircraft applications. The impacts of different hole making methods with constant or varied machining parameters across the stacked structures have been investigated. The resulting exit burr, hole surface roughness/microstructural change and fatigue behaviour of the machined stacks have been characterized in detail. Results show that the exit burr formation is most severe for conventional drilling and least burr is produced in helical milling coupons. Deploying varying parameters (i.e. optimal parameters for each individual metal layer) across the stacks can effectively reduce the burr formation in conventional drilling and peck drilling. 3D surface morphology shows that Al 2024-T3 hole surface contains multiple scratches and trenches, while Ti-6Al-4V hole surface features regular feed marks. Helical milling leads to the highest Al 2024-T3 hole surface roughness, which can be attributed to the abrasion caused by the evacuated Ti-6Al-4V chips. Sub-surface microstructural analysis shows that the Ti-6Al-4V layer is more prone to machining-induced microstructural change (i.e. white layer formation and/or grain plastic deformation along machining direction). The relatively low fatigue performance of stacks produced by conventional drilling and peck drilling with constant parameters can be related to the presence of the brittle Ti-6Al-4V white layer in these coupons. Deploying varied parameters across stacks in conventional drilling and peck drilling can effectively eliminate Ti-6Al-4V white layer formation and improve the stacks fatigue life by 72% and 38%, respectively. Helical milling leads to the longest stack fatigue life (~ 100% and 40% greater than conventional drilling and peck drilling, respectively).

Genomic analysis and finding of candidate genes for Nilaparvata lugens (stål) resistance in Indian pigmented and other indigenous rice genotypes

Rice production is facing serious threats due to frequent outbreak of brown plant hopper, Nilaparvata lugens (Stål.) population. Globally, four biotypes of N. lugens has been recorded, of which biotype-4 is the utmost damaging one prevailing in Asian subcontinents particularly in India. Therefore, effective management of N. lugens requires durable resistant rice variety with multiple resistant traits and genes. Hence, in the present study 268 rice genotypes were screened against N. lugens. From initial screening results, 96 genotypes were selected for further genotyping using 93 molecular markers linked to 26 different N. lugens resistant (R) genes. Genetic analysis revealed the mean genetic diversity of 0.275 and polymorphic information content of 0.240 for all 93 markers. Genetic association through cluster and population structure analysis clearly differentiated the 96 genotypes into three major genetic groups with resistant genotypes grouped in a separate cluster. Likewise, Principal co-ordinate analysis supported the above claim with susceptible, moderately resistant and resistant genotypes accommodated in separate components. Further, genetic variation among population showed a 92% variation among individuals of the population and only 8% between populations. Marker trait association via generalized linear model (GLM) and multi linear model (MLM) picked out five markers for their significant association with different phenotypic parameters such as percent damage, nymphal survival, feeding mark and honeydew excretion. Three markers viz. RM19291 (Bph30), RM28472 (Bph18) and RM28449 (Bph17) were common for both GLM and MLM analysis. These identified resistant genes in rice landrace will serves as the source for development of durable resistant variety against N. lugens.

Effect of EDMed rake face grooves on the chip breaking capability of twist drills during deep hole drilling of Al 6061 aluminum alloy

ABSTRACT Deep hole drilling of ductile materials like Al6061 with conventional twist drills is challenging due to premature tool failure caused by chip clogging. Chip breakers, in the form of grooves of varying angles (0°, 5° & 10°) and depth (0.4 & 0.5 mm), created using EDM on the rake face, are proposed to overcome chip clogging. Tool wear, hole roughness, and diameter deviation were measured and analyzed along with chip morphology study for the six grooved tools and compared with plain drill. The grooved tools were successful in breaking the chips which allows for easy evacuation without any clogging. Grooved drills produced desired spiral chips compared to string chips produced by plain drill thus resulting in lesser tool wear rate. While the grooved tools showed stable but slightly higher roughness values, the conventional tools exhibited a linear increasing trend as the drilling progressed. The machined hole surfaces had defects such as feed marks, pitting, grooves, and burnished surfaces. The grooved tools produced comparatively more diameter deviation probably because the well broken chips entered into the drill land/hole surface space. From the results it is clear that groove angle and depth have significant effect on the drill machinability characteristics.

Analysis of defects on machined surfaces of aluminum alloy (Al 7075) using imaging and topographical techniques

Aluminum alloys 7075 (Al 7075) are widely used for various industrial components in which machining operations are often conducted during their manufacturing process. However, the machining operations could introduce defects on the machined surfaces of the components which will be carried over and may lead to either issues in the subsequent fabrication process or failure during the products' service life. This study investigates the machined surface's defects of Al 7075 underwent drilling operations using imaging and topographical techniques which include optical microscope, scanning electron microscope and 3D surface profiler. Surface roughness was analysed with respect to the surface defects to investigate the correlation between the roughness parameters and topographical features of the machined surfaces. The defects found on the machined surfaces of Al 7075 are microcrack, adhesion, feed mark and burr. Surface roughness was found to be highly influenced by topographical features particularly feed mark. Thus, in addition to measuring the roughness, inspection through imaging and 3D topographic techniques is important for analyzing the surface characteristic in order to determine the defects, hence deducing the detailed surface features and deformation caused by the drilling operations.

Areal surface texture and tool wear analysis from machining during powder bed fusion

Coupling additive manufacturing with milling changes the interaction between the cutting tool and workpiece. The resulting effect on tool wear and surface integrity is poorly understood. Maraging steel printed via powder bed fusion was peripherally milled in the presence of un-melted metallic powder surrounding the printed part. Areal surface parameters, microhardness, and tool wear were analyzed. Results showed that milling within powder decreased surface roughness and introduced a weak orthogonal texture between the feed marks and printed layers. Milling without powder caused a more pronounced inclined texture. Milling within powder accelerated flank wear while milling without powder accelerated crater wear.

Study on surface integrity of titanium alloy machined by electrical discharge-assisted milling

• Electrical discharge-assisted milling (EDAM) can improve the surface integrity of Ti-4Al-6 V. • EDAM can reduce the surface roughness compared with conventional milling (CM). • Compared with CM, the residual tensile stress generated by EDAM is smaller. • The microhardness of machined surface after EDAM is relatively smaller than CM. • Moderate capacitance has more positive influence for surface integrity. Electrical discharge-assisted milling (EDAM) is an efficient machining process for titanium alloys according to previous studies. However, a complete understanding of the surface integrity of titanium alloy machined with EDAM is not yet sufficient. Therefore, in this paper, surface defects such as chip layer adhesion, debris, feed marks, and burrs were investigated and identified. Among them, the adhesion of the chip layer is the most common surface defect and is the factor that has the greatest influence on the surface quality. In addition, surface roughness, micro-hardness, and residual stress were analyzed and discussed. The results show that the surface roughness of EDAM is significantly improved compared to conventional milling (CM). Also, the residual stress generated by EDAM is much smaller than that of CM, and the main type of residual stress is residual compressive stress. Similarly, the surface microhardness after EDAM is also slightly smaller than that of CM. This increased surface integrity is due to the material softening effect due to the heat generated by the discharge spark. Consequently, EDAM is a good candidate method for efficient machining of titanium alloys.

On the Machinability Evolution in Asymmetric Milling of TC25 Ti Alloy Aiming at High Performance Machining.

In this paper, the evolutions of cutting force, cutting temperature, and surface roughness, and the corresponding machinability in asymmetric up-milling of TC25 alloy are investigated. The results indicated that radial depth of cut generated opposite influence on the cutting force/cutting temperature versus surface roughness. The reason can be accounted as the intertwining of feed marks at low radial depth of cut, and the mechanism of hard cutting at a high radial depth of cut. Moreover, the asymmetry has a significant effect on the machinability in asymmetry up-milling TC25 alloy. Changing the asymmetry, i.e., the radial depth of cut, can alter the machinability while maintain the balanced development of various indexes. The machinability reaches the best when the radial depth of cut is ae = 8 mm. The axial depth of cut and feed per tooth should be selected as large as possible to avoid work hardening and to improve machining efficiency in asymmetric up-milling TC25 alloy. The cutting speed should be controlled within Vc = 100–120 m/min to obtain better machinability. On the basis of this research, it is expected to find optimized milling parameters to realize high efficiency milling of TC25 alloy.

Turning processes and mechanism of compacted graphite iron used for high performance engine

Compacted graphite iron (CGI) represents a new material for high-performance diesel engines of next generation. Compared with gray cast iron (GCI), it can enhance the cylinder pressure while reducing the weight of the engine. However, not all of the tools and parameters used to process GCI are applicable to CGI. The tool life, which is characterized by the height of flank wear in machining GCI, is 10–20 times that of GCI. In order to deeply study the machining gap between CGI and GCI, the machined surface morphology of CGI-450 and GCI-280 with different surface roughness was investigated. In addition, tool wear and cutting temperature were also monitored. Finally, the chip morphology after the first cutting was analyzed. The results show that the primary surface defects, with Ra = 2.0 μm, of CGI-450 are graphite cavities and feed marks, while those of GCI-280 are plastic flow and graphite cavities. The tool wear patterns of turning CGI-450 and GCI-280 are the same, and the maximum flank face value reaches 133 μm and 102 μm, respectively. If Ra =1.6 μm is the tool failure criterion, the tool life for machining CGI-450 is 1.73 times that for cutting CGI-450. The serration depth and chip opening angle after machining CGI-450 are larger than those of GCI-280. The cutting temperature increases with the surface roughness within a certain range, and the temperature of CGI-450 is 20% higher than that of GCI-280.

Investigation of Surface Quality for Minor Scale Diameter of Biodegradable Magnesium Alloys during the Turning Process Using a Different Tool Nose Radius

The main objective of the study is to analyze the various cutting parameters to investigate the surface quality of the minor scale diameter of magnesium alloy in the dry turning process using a different tool nose radius (r). The surface roughness (Ra) was gauged, and micro-images produced by scanning electron microscopy (SEM) were reviewed to evaluate the machined surface topography. The analysis of variance (ANOVA), linear regression model and signal-to-noise (S/N) ratio were applied to investigate and optimize the experimental conditions for surface roughness. The study results imply that the feed rate and tool nose radius significantly affected the surface quality, but the spindle speed did not. The linear regression model is valid to forecast the surface roughness. The cutting parameters for optimum surface quality are a combination of a spindle speed of 710 rpm, a feed rate of 0.052 mm/rev and a tool nose radius of 1.2 mm. The machined surface topography contains the feed marks, micro-voids, material side and material debris, but they become smaller and decrease at a lower feed rate, larger tool nose radius and higher spindle speed. These results show the good surface quality of magnesium alloys in a dry turning process, which could be applied in implant, orthopedic and trauma surgery.

The Effect of TiN-, TiCN-, TiAlN-, and TiSiN Coated Tools on the Surface Defects and Geometric Tolerances of Holes in Multi-Spindle Drilling of Al2024 Alloy

The integrity of machined holes depends on many parameters, some of which are related to the cutting tool (geometry, coating, material). Other influential parameters are related to the machining process variables (spindle speed, feed rate, workpiece material), all of which can affect the quality of the hole and drilling induced damage on its surface. This study investigates the effect of uncoated tools and four types of tool coatings (TiN-, TiCN-, TiAlN-, and TiSiN) on the hole quality and its microstructure. The study analyzed several hole geometrical metrics, namely hole size, circularity, cylindricity, and perpendicularity of an Al2024 aluminum alloy using a multi-spindle drilling process that utilizes three drills capable of creating multiple holes simultaneously. The results showed that the uncoated carbide drill gave a high-hole quality at low spindle speed. Regarding the coated drills, TiCN coated drills produced holes with the least deviation, circularity, cylindricity and perpendicularity at high spindle speeds. TiSiN–carbide coated drills produced the most oversized holes and noticeable damage and deformations on their surface following TiAlN and TiN. The common surface damage found on the inner hole surface was smearing, feed marks, and metal debris adhesion. The ANOVA results revealed that the tool type had the highest percentage contribution that mainly affected the hole quality.

Surface morphology characterization of unidirectional carbon fibre reinforced plastic machined by peripheral milling

This paper aims to characterise surface morphology and 3D roughness parameters of unidirectional carbon fibre reinforced plastic (UD-CFRP) milled at 0°, 45°, 90°, and 135° fibre orientation angles (FOAs). Side milling experiments are conducted on UD-CFRP laminates. Surface damage forms and texture direction of milled surface are analysed. Spatial frequency of defects on CFRP surface is quantitatively determined using radially averaged 2D PSD. The kinematic-dynamic surface topography is reconstructed considering feed, runout and vibration, then the ideal roughness parameters, Sa, Sq, Ssk, and Sku are calculated and compared with the measured ones, finally the material factor-induced roughness components are quantified. Results show that CFRP surface has no regular feed marks. The frequency of fibre breakage or surface defects is greater than tooth passing frequency. FOAs sorted by their average Sa in descending order is 135°>90°>45°>0°, where surface defects contribute 93.9%, 77.1%, 73.2%, 72.2% of the total roughness respectively, which suggests that surface defects show a more important role than tool kinematics and vibration in formation of milled surface. The negative Skewness (Ssk < 0) and high Kurtosis (Sku = 4.0–11.5) of milled surface signify porosity and the presence of many anomalous deep valleys in milled surface, respectively.

Evaluation of the Surface Defects and Dimensional Tolerances in Multi-Hole Drilling of AA5083, AA6061, and AA2024

Drilling is one of the most performed machining operations for riveting and assembly operations in many industrial sectors. The accuracy of the drilled holes and their surface finish play a vital role in the longevity and performance of the machined components, which, in turn, increase productivity. Therefore, this study investigated the effect of the multi-spindle drilling process on dimensional hole tolerances, such as hole size, circularity, cylindricity, and perpendicularity. In addition, the surface defects formed in the holes were examined using scanning electron microscopy. Three aluminium alloys, AA2024, AA6061, and AA5083, which are commonly used in the aerospace, automotive, and marine sectors, were chosen as the study materials. The results showed that the holes drilled in AA2024 gave less circularity error, cylindricity error, and perpendicularity error. In the case of hole size, the holes drilled in AA6061 were less deviated from the nominal size following holes drilled in AA2024 and AA5083 alloys. Surface damage in the form of metal debris adhesion, smeared material, side flow, and feed marks was found on the inner hole surface. Holes drilled in AA5083 alloy had the worst surface finish and were the most oversized, which was associated with noticeable damage and deformations in their inner surface. The ANOVA results revealed that the spindle speed was more influential than feed and mainly affected the hole size and cylindricity errors. However, in the case of circularity error and perpendicularity error, drilling parameters were found to be insignificant.

Genetic dissection and identification of candidate genes for brown planthopper, Nilaparvata lugens (Delphacidae: Hemiptera) resistance in farmers’ varieties of rice in Odisha

Globally, rice production is severely affected by brown planthopper (Nilaparvata lugens) populations. Among the four different biotypes of N. lugens reported worldwide, biotype 4 is the most damaging and prevalent insect pest in South East Asian countries, especially in the Indian sub-continent. Management of this pest with resistant genotypes is effective and thus it has received considerable attention worldwide. In the present work, a total of 600 farmer's varieties (FVs) were screened against N. lugens and subsequently 104 panel populations were selected for genotyping. Marker-trait association and genetic diversity were worked out for 87 molecular markers linked to 34 different N. lugens resistance genes. The average content of polymorphism information was 0.354 for 34 genes with a threshold level 0.018 to 0.750. One hundred and four FVs were categorized into three main genetic groups according to cluster analysis and population structure. Resistant and moderately resistant FVs were separately distributed according to principal co-ordinate analysis. Analysis of molecular variance displayed maximum diversity (83%) within population and minimum diversity (17%) between populations. In both generalized linear model (GLM) and multi linear model (MLM), eight markers linked to Bph genes were found to be common for four different phenotypic parameters like honeydew excretion, nymphal survival, percent damage, and feeding mark. Our study suggests that presently available monogenic BPH resistant lines were not withstanding BPH biotype-4 pressure. Thus, the reported resistance genes either alone or in combination could be introgressed into elite varieties with genomic approach to develop robust resistant rice varieties against N. lugens biotype 4. Further, the identified FVs are useful for novel R genes identification, host–insect interaction, and genomic studies.

Ultrasonic assisted turning of AISI 52100 steel using nanoparticle-MQL method

High cutting force and high cutting tool-chip interface temperature occur during machining of high strength materials like AISI 52100 by using conventional turning method and this makes to the difficult machining operation. Besides, in conventional turning (CT) of these materials, which has high abrasion resistance and hardness properties, an additional process such as grinding is required to achieve the desired surface quality. Ultrasonic assisted turning (UAT) method has been widely used in the machining industry in recent years, as it exhibits better surface quality, lower cutting forces, and cutting temperature than the CT method. This paper focused on experimentally and statistically determining the effects of different cutting parameters and cooling conditions (dry and minimum quantity lubrication-MQL) on surface roughness, workpiece surface texture, tangential direction cutting force, and cutting tool-workpiece interface temperature in the machining of AISI 52100 material by using UAT and CT methods. The experimental results revealed that significant improvements determined in the cutting forces and the surface roughness occurred in UAT compared to CT in all the cooling conditions. However, the increasing cutting speeds caused to observe higher interface temperature values in dry turning by the UAT method. Variance Analysis (ANOVA) was carried out to determine the significance grade of independent variables on dependent variables. According to ANOVA results, while the cutting speed is the most important factor on the surface roughness and the cutting zone temperature, and the cooling method is the most important factor on the cutting force. The effects of turning methods on corresponding surface topography, including surface defects, were evaluated. It is determined that in the surface topography analysis, feed marks are the main texture of the workpiece in the CT method while micro-level indentations and protrusions occurred on the workpiece surface in the UAT method.

Modelling of machined surface topography and anisotropic texture direction considering stochastic tool grinding error and wear in peripheral milling

This paper establishes a new model for predicting machined surface topography and anisotropic texture direction in peripheral milling. Unlike previous models, this model takes into account the largest number of influential factors, i.e., tool setting error (radial offset and axial tilt), static tool deflection, forced vibration, chatter vibration, and stochastic tool grinding error and wear (STGEW). STGEW, quantified by the normal distribution (μ, σ2), is incorporated into the model for the first time. The model predictions for 3D surface topography, anisotropic texture direction, 2D surface profile or roughness agree remarkably well with experimental or published results, under both stable and unstable milling conditions. It is found that static deflection slightly attenuates the effect of tool setting error on roughness. Even machining with fresh tools or tools with very small cutting length (<15 mm) and wear (VB∼5 μm), inherent STGEW creates random scratches with different geometries parallel to feed direction on the milled surface. STGEW expands the difference of roughness in axial direction. STGEW induces an additional surface texture in feed direction, which co-exist with axial texture contributed by feed marks when standard deviation σ to feed rate ft ratio is small. As σ increases, (1) feed marks are gradually obliterated by scratches, and surface texture is only oriented in feed direction; (2) the mean and variance of roughness in both directions increase, and axial roughness prevails transverse toughness at high σ. The study discovers that, STGEW, even with small σ (e.g., σ=[0.01 μm, 0.1 μm]), is an important factor affecting surface topography, anisotropic surface texture direction and roughness that cannot be ignored, especially in the case of low-feed machining, e.g., ft = 0.05 mm, which is commonly adopted in finish-milling of difficult-to-cut materials. The proposed model can be used to reliably and accurately predict surface topography, surface roughness and surface texture direction in peripheral milling operation.

Comprehensive study on the cutting specific energy and surface roughness of milled in situ TiB2/Al composites and Al alloys

Although TiB2 particles improve the wear resistance and hardness of in situ TiB2/Al composites, TiB2 particles bring challenges for machining TiB2/Al composites. In order to study the difference between the cutting performance of aluminum alloys and TiB2/Al composites, the milling experiment of 2024 aluminum alloys, 7075 aluminum alloys, TiB2/2024 composites, and TiB2/7075 composites was conducted. The cutting specific energy, the milling force coefficient, and machined surface roughness are analyzed. The results show that the cutting specific energy and cutting force coefficient of TiB2/Al composites are higher than those of the conventional aluminum alloys. In addition, the machined surface profile and its spectrum are analyzed. The results indicate tool vibration is the main reason for the abnormal high surface roughness, especially for conventional aluminum alloys. The cutting stability of TiB2/Al composites is better than that of conventional aluminum alloys. TiB2 particles hinder the plastic deformation of the matrix alloy, reducing the tool feed marks, which makes the surface roughness of TiB2/Al composites lower.

Effect of cooling strategies on performance and mechanism of helical milling of CFRP/Ti-6Al-4 V stacks

Hole-making for Carbon Fiber Reinforced Plastics (CFRP)/Ti-6Al-4 V stacks is crucial for the assembling strength of aircraft structure parts. This work carried out experimental work for helical milling (HM) of the stacks with sustainable cooling/lubrication (dry, MQL and cryogenic) conditions. Cutting forces and temperatures at the CFRP layer, Ti-6Al-4 V layer and the interface of stacks were obtained by a developed measuring system. The temperatures in CFRP machining at cryogenic condition varied from −167 °C to −94 °C, which were much lower than those at dry and MQL conditions. The maximum temperature near the interface of stacks for the ninth hole was higher than 240 °C due to heat conduction from Ti-6Al-4 V layer. The hole quality, hole diameter and tool wear mechanism at different cooling/lubrication conditions were presented and discussed. MQL condition generated mainly extrusion fracture for the fibers, due to the reduced friction effect compared with dry condition. MQL was helpful to reduce the feed mark at the hole surface of Ti-6Al-4 V alloy. The flank wear of cutting edge at MQL condition was better than those at dry and cryogenic conditions. Cryogenic cooling contributed to better CFRP surface with smaller delamination and hole entrance damage due to the increased resin strength and fiber brittleness. The damage near the entrance of CFRP were analyzed by the contact state of cutting edges and fibers. Additionally, hole diameters near the exit of CFPR layer were larger than other test positions. This work provided feasible processes for improving hole quality and tool life in hole-making of CFRP/Ti-6Al-4 V stacks.

Metrological analysis of surface quality aspects in minimum quantity cooling lubrication

This study focuses on metrological aspects of cooling methods that contribute to the development of sustainable production using a very small amount of active medium. This paper presents the evaluation of surface integrity aspects during turning of AISI 1045 steel with various cooling/lubricating techniques such as machining in dry conditions, MQCL method, MQCL method with extreme pressure/anti-wear additive (EP/AW). Initially, the experiments were performed with the parameter space investigation method. Then, the surface integrity aspects were characterized by the parametric evaluation of surface topography and the results of strain hardening. With an application of MQCL + EP/AW turning, surfaces with more even distribution of valleys and peaks were generated, which resulted, inter alia, in the reduction of selected roughness height parameters (Sa, Sp, Sv). The signal of power spectral density (PSD) analysis also confirmed that the presence of surface topography components is highly responsible for regular feed marks.

An elongate hadrosaurid forelimb with biological traces informs the biogeography of the Lambeosaurinae

AbstractAlthough the fossil record of the Late Cretaceous eastern North American landmass Appalachia is poor compared to that from the American West, it includes material from surprisingly aberrant terrestrial vertebrates that may represent relictual forms persisting in relative isolation until the end of the Mesozoic. One intriguing question is to what extent eastern and western North American faunas interspersed following the closure of the Western Interior Seaway during the Maastrichtian Stage of the Late Cretaceous ca. 70 Ma. Isolated remains from the Atlantic Coastal Plain in New Jersey have been preliminarily identified as the bones of crested lambeosaurine hadrosaurids, a derived clade known from the Cretaceous of Asia, western North America, and Europe, but have not been formally described. We describe the partial forelimb of a large hadrosaurid from the late Maastrichtian New Egypt Formation of New Jersey. The ulna preserves multiple deep scores identifiable as shark feeding marks, and both bones show ovoid and circular marks attributable to invertebrates. This forelimb is very similar to another partial antebrachium from the same area that shows evidence of septic arthritis. Both these specimens and a complete humerus from the same unit are closely comparable to the lower forelimbs of lambeosaurines among hadrosaurid dinosaurs. Although the absence of lambeosaurine synapomorphies observable on the New Egypt Formation forelimbs precludes their definite referral to Lambeosaurinae, they show that a morphotype of large hadrosauromorph with distinctly elongate forelimbs existed in the latest Maastrichtian of eastern North America and allow for a revision of the latest Cretaceous biogeography of crested herbivorous dinosaurs.