This study analyses the lithic landscape and the selection of rocks used to manufacture Fishtail points (FP) in southern Brazil, their designs, and some functional aspects. In order to identify the offer of lithic resources, we carried out several surveys throughout 15 months in 47 counties in the Southern Brazil covered by the Botucatú - Serra Geral Vulcano Sedimentary Complex. The lithic composition of numerous hill slopes, fallen rocks, and accumulations of pebbles and boulders in the riversides was evaluated. The results show that basalts (including a small proportion of andesites and rhyodacites-rhyolites), and silicified sandstones, are ubiquitous in the landscape. Conversely, non-translucent cherts are scarce, so their acquisition would have been time-consuming. However, these local cherts were the rocks mostly used to manufacture these points, being another example of the selectivity for high quality rocks by Paleoamerican hunter-gatherers. The same cherts selected in southern Brazil to produce the FP were used to manufacture other point-types by local hunter-gatherers of the early and middle Holocene grouped in the so-called “Umbú Tradition”. Not a single FP of the entire collection analyzed here was made from silicified limestones, which is one of the most common raw materials among the Uruguayan FPs, nor were they made from quartzites as were most of the FPs of the Pampean plains. Regarding to the designs of these projectiles, some morphotypes appear to have been designed to produce multiple injuries through successive thrusts and withdrawals in the bodies of the prey, while in others, the design seems to have favoured penetration and fixation on the prey, suggesting in this case, a single shot technique for each projectile. As the maintenance process unfolded, especially for points below ~ 80 mm in length, they show features that negatively impacted their efficiency, including distinct asymmetries, somewhat open front angles, a decrease in the cutting perimeter and cross-sectional area, an increase in the bevel angle of the blade edges, and a tendency to a conical cross-section. Behaviours intended to counteract these problems were maximizing the length of the leading edge, maintaining the symmetry and the triangular blade resting on straight shoulders, and maintaining the aerodynamic properties as much as it were possible, in order to improve their lethality and the fixation capacity. Beyond these rejuvenation processes, three different morphotypes of points appear to be included within the sample. The first includes points over 120 mm and ~ 80 g in weight, with triangular or slightly lanceolate limbs, which mostly present straight shoulders, but there are also examples of rounded shoulders. The second design corresponds to projectiles between 110 and 87 mm and ~30 g in weight, with triangular or slightly lanceolate blades and straight shoulders. The third design presents the classic shape of these projectiles, with a fish silhouette, with maximum lengths below 90 mm, with a more robust and conceptually different design, where the angles of the edges of the blades and of the shoulders are equal, perhaps with the intention to facilitate the spear withdrawal to produce multiple injuries.

中文翻译：

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巴西南部鱼尾弹头原料及功能设计

本研究分析了巴西南部用于制造鱼尾尖 (FP) 的岩石景观和岩石的选择、它们的设计和一些功能方面。为了确定岩质资源的供应，我们在 15 个月内在巴西南部博图卡图 - 塞拉热拉尔火山沉积复合体覆盖的 47 个县进行了多次调查。评估了河边众多山坡、落石以及卵石和巨石堆积物的岩石成分。结果表明，玄武岩（包括一小部分安山岩和流纹岩-流纹岩）和硅化砂岩在景观中无处不在。相反，非半透明燧石稀缺，因此它们的获取会很耗时。然而，这些当地的燧石是主要用于制造这些点的岩石，是古美洲狩猎采集者对优质岩石的选择性的另一个例子。在巴西南部选择用于生产 FP 的相同燧石被称为“Umbú 传统”的全新世早期和中期的当地狩猎采集者用于制造其他点型。这里分析的整个集合中没有一个 FP 是由硅化石灰石制成的，硅化石灰石是乌拉圭 FP 中最常见的原材料之一，它们也不是像 Pampean 平原的大多数 FP 那样由石英岩制成。关于这些射弹的设计，一些形态类型似乎被设计为通过对猎物身体的连续推力和撤回来产生多重伤害，而在其他形态中，该设计似乎倾向于穿透和固定在猎物上，在这种情况下，建议对每个射弹使用单次射击技术。随着维护过程的展开，特别是对于长度低于 80 毫米的点，它们显示出对其效率产生负面影响的特征，包括明显的不对称性、有点开放的前角、切割周长和横截面积的减少、刀片边缘的斜角，以及锥形横截面的趋势。旨在解决这些问题的行为是最大化前缘的长度，保持对称性和搁在直肩上的三角形叶片，并尽可能保持空气动力学特性，以提高它们的杀伤力和固定能力。除了这些恢复活力的过程之外，样本中似乎包含三种不同形态的点。第一种包括超过 120 毫米、重约 80 克的点，四肢呈三角形或略披针形，多呈直肩，但也有圆肩的例子。第二种设计对应于 110 至 87 毫米和约 30 克重量的射弹，具有三角形或略呈披针形的刀片和直肩。第三种设计呈现了这些弹丸的经典形状，鱼形轮廓，最大长度低于 90 毫米，采用更坚固且概念上不同的设计，叶片边缘和肩部的角度相等，也许与意图便于长矛撤退，产生多处伤害。第一种包括超过 120 毫米、重约 80 克的点，四肢呈三角形或略披针形，多呈直肩，但也有圆肩的例子。第二种设计对应于 110 至 87 毫米和约 30 克重量的射弹，具有三角形或略呈披针形的刀片和直肩。第三种设计呈现了这些弹丸的经典形状，鱼形轮廓，最大长度低于 90 毫米，采用更坚固且概念上不同的设计，叶片边缘和肩部的角度相等，也许与意图便于长矛撤退，产生多处伤害。第一种包括超过 120 毫米、重约 80 克的点，四肢呈三角形或略披针形，多呈直肩，但也有圆肩的例子。第二种设计对应于 110 至 87 毫米和约 30 克重量的射弹，具有三角形或略呈披针形的刀片和直肩。第三种设计呈现了这些弹丸的经典形状，鱼形轮廓，最大长度低于 90 毫米，采用更坚固且概念上不同的设计，叶片边缘和肩部的角度相等，也许与意图便于长矛撤退，产生多处伤害。但也有圆肩的例子。第二种设计对应于 110 至 87 毫米和约 30 克重量的射弹，具有三角形或略呈披针形的刀片和直肩。第三种设计呈现了这些弹丸的经典形状，鱼形轮廓，最大长度低于 90 毫米，采用更坚固且概念上不同的设计，叶片边缘和肩部的角度相等，也许与意图便于长矛撤退，产生多处伤害。但也有圆肩的例子。第二种设计对应于 110 至 87 毫米和约 30 克重量的射弹，具有三角形或略呈披针形的刀片和直肩。第三种设计呈现了这些弹丸的经典形状，鱼形轮廓，最大长度低于 90 毫米，采用更坚固且概念上不同的设计，叶片边缘和肩部的角度相等，也许与意图便于长矛撤退，产生多处伤害。